USMLE : ICM And Pathology Questions! Trivia Quiz

Explanation
MEDULLOBLASTOMA is the most frequently encountered intracranial neuroectoclermal tumor in children. Microscopically, medulloblastoma reveals a primitive small-celled malignant tumor forming Homer-Wright rosettes. The nuclei are closely packed, hyperchromatic, relatively uniform and round, oval, or carrot shaped. Dissemination through the CSF is a common complication. The tumor is highly malignant. However, the tumor is very radiosensitive. With total excision and radiation, the 5-year survival rate is as high as 75%.
NEUROBLASTOMA is one of the common solid tumors of childhood and can arise from adrenals or extra-adrenal sites. Cerebellar neuroblastomas are rare, and they arise in the early part of the first decade and show a highly aggressive clinical behavior. The majority are supratentorial, massive, and multicystic. Histologically, they are highly cellular, showing cells that are small with hyperchromatic nuclei and are arranged in solid sheets. A slightly fibrillated matrix traversed by delicate neurites is characteristic. They are negative for GFAP and do not stain with PTAH indicating the absence of glial component. Characteristic Homer-Wright rosettes with tumor cells at the periphery and young nerve fibrils at the center may be present.
CEREBELLAR ASTROCYTOMA predominantly occurs in children. They are characterized by a biphasic pattern. There are bipolar fibrillated and elongated cells packed in bundles with perivascular arrangements and there are stellate cells with short processes with a lacy pattern and show microcystic changes. Also seen are Rosenthal fibers, granular hyaline deposits, and eosinophilic intracytoplasmic bodies. These tumors grow slowly and have a benign course.
OLIGODENDROGLIONNAS constitute about 5 to 15% of gliomas and are most common in the fourth and fifth decades. The lesions are found in cerebral hemispheres, with a predilection for the white matter. Grossly, they are well- circumscribed, gelatinous, often with cyst formation, areas of hemorrhage and calcification. Microscopically, they are characterized by round cells with a small darkly staining nucleus, clear cytoplasm, and clearly defined cell membrane. In general, they have a better prognosis than astrocytomas.
EPENDYNNONNAS most often arise next to the ependyma lined ventricular system. They commonly occur near the 4th ventricle in the first 2 decades and in spinal cord in adults. Microscopically, they are characterized by ependymal rosettes, which are duct-like structures with a round or elongated central lumen around which columnar cells are arranged concentrically with basal nuclei.

Explanation
Not all dementing disorders manifest with the same clinical features. Although there is considerable overlap in clinical symptomatology among different types of dennentias, making clinical diagnosis somewhat problematic, there are classic presentations that allow identification of a specific form of dementia with a high degree of confidence. In this case, the patient has symptoms due to frontal lobe damage, e.g., disinhibition, impaired judgment, and personality changes. Furthermore, MRI demonstrates a specific pattern of cortical atrophy, restricted to the frontal lobes and anterior portion of the temporal lobes. This combination points toward a group of dementias called frontotemporal dementia, the most frequent form of which is Pick disease. Other forms of frontotemporal dementia are very infrequent. Remember: frontal symptoms in conjunction with frontotennporal atrophy = frontotemporal dementia/Pick disease.
Alzheimer's disease is the most frequent form of dementia in industrialized countries. Although symptoms due to frontal damage may be present in Alzheimer's disease, they are usually associated with a more generalized impairment of higher neurologic functions, e.g., language, memory, and learned movements. In addition, cortical atrophy in Alzheimer's disease is widespread and not limited to the frontal and anterior temporal lobes.
Creutzfeldt-Jacob disease represents the prototype of prion diseases. Cortical atrophy is not a prominent feature of Creutzfeldt-Jacob disease, which manifests with personality changes, memory loss, and seizures, leading to death after a rapid clinical course (a few months to 1 year).
Dementia with Lewy bodies, also known as diffuse Lewy body disease, is one of the most common forms of dementia in Western countries, possibly more common than vascular dementia. It is characterized by widespread formation of Lewy bodies in the substantia nIgra, limbic cortex, and subcortical nuclei, such as the basal nucleus of Meynert. Extrapyrannidal symptoms similar to Parkinson's disease manifest in this form of dementia as a result of degeneration of dopamlnergic pathways.
Vascular dementia is an umbrella term encompassing dementing conditions that arise from pathology of large or small cerebral vessels. It manifests with memory loss associated with focal neurologic symptoms depending on the location of damage. MRI would identify old or recent infarcts, as well as white matter disease. Conditions associated with vascular dementia include the following: multi-infarct dementia, which is caused by multiple, scattered brain infarcts secondary to atherosclerosis of large arteries of the circle of Willis and/or carotid arteries; Binswanger disease, which involves rarefaction of cerebral white matter and is caused by hypertension-related arteriolosclerosis; lacunar infarcts, which consist of small (< 1 cm) infarcts in the striatum and thalamus and is related to arteriolosclerosis.

Explanation
Meningiomas are generally benign, encapsulated tumors that once diagnosed, can be completely removed surgically, although meningiomas in the area of the brainstem may be more difficult to remove. Meningiomas typically compress the underlying cerebral cortex, leading to cortical dysfunction of that particular area. In this case, our patient likely suffered from a frontal lobe meningioma. Astrocytonnas (gliomas) are very invasive and are not typically susceptible to surgical resection. Acoustic neuroma and pinealonnas are more difficult to remove surgically and the surgery is not without its consequences. For instance, removal of an acoustic neuroma typically causes facial paralysis and deafness.

Explanation
MEDULLOBLASTOMA is the most frequently encountered intracranial neuroectoclermal tumor in children. Microscopically, medulloblastoma reveals a primitive small-celled malignant tumor forming Homer-Wright rosettes. The nuclei are closely packed, hyperchromatic, relatively uniform and round, oval, or carrot shaped. Dissemination through the CSF is a common complication. The tumor is highly malignant. However, the tumor is very radiosensitive. With total excision and radiation, the 5-year survival rate is as high as 75%.
NEUROBLASTOMA is one of the common solid tumors of childhood and can arise from adrenals or extra-adrenal sites. Cerebellar neuroblastomas are rare, and they arise in the early part of the first decade and show a highly aggressive clinical behavior. The majority are supratentorial, massive, and multicystic. Histologically, they are highly cellular, showing cells that are small with hyperchromatic nuclei and are arranged in solid sheets. A slightly fibrillated matrix traversed by delicate neurites is characteristic. They are negative for GFAP and do not stain with PTAH indicating the absence of glial component. Characteristic Homer-Wright rosettes with tumor cells at the periphery and young nerve fibrils at the center may be present.
CEREBELLAR ASTROCYTOMA predominantly occurs in children. They are characterized by a biphasic pattern. There are bipolar fibrillated and elongated cells packed in bundles with perivascular arrangements and there are stellate cells with short processes with a lacy pattern and show microcystic changes. Also seen are Rosenthal fibers, granular hyaline deposits, and eosinophilic intracytoplasmic bodies. These tumors grow slowly and have a benign course.
OLIGODENDROGLIOMAS constitute about 5 to 15% of gliomas and are most common in the fourth and fifth decades. The lesions are found in cerebral hemispheres, with a predilection for the white matter. Grossly, they are well- circumscribed, gelatinous, often with cyst formation, areas of hemorrhage and calcification. Microscopically, they are characterized by round cells with a small darkly staining nucleus, clear cytoplasm, and clearly defined cell membrane. In general, they have a better prognosis than astrocytomas.
EPENDYMOMAS most often arise next to the ependyma lined ventricular system. They commonly occur near the 4th ventricle in the first 2 decades and in spinal cord in adults. Microscopically, they are characterized by ependymal rosettes, which are duct-like structures with a round or elongated central lumen around which columnar cells are arranged concentrically with basal nuclei.

Explanation
Dementia due to Pick's disease is a progressive neurodegenerative disease affecting the frontal and temporal lobes, which is characterized by frontal lobe involvement in which the patient may have emotional apathy or lability and disinhibition. The temporal lobe affectation is demonstrated by his problems with language and carrying out executive tasks. The symptoms usually appear between the ages of 50 to 60 years old. Usually the person exhibits some emotional disturbances in the beginning, and then years later, progresses into having problems with language and executive functioning. The cause of the disease is unknown. It can be diagnosed by the finding of intraneuronal argentophillc inclusions (Pick bodies) and swollen neurons (Pick cells) in the frontal and temporal areas of the brain. Functional neuroinnaging such as Positron Emisson Tomography (PET) show hypometaboiisnn in these regions before the atrophy occurs and becomes apparent on the MRI.
Dementia due to Alzheimer disease is another progressive neurodegenerative disease that, in contrast to the above, produces brain lesions. This type of dementia is seen in 55% of the cases of dementia. It occurs with more frequency in populations of increasing age. It is rarely seen in those younger than 50 years old. There seems to be a genetic predisposition especially seen on chromosomes 14, 19, and 21. Other factors may also be involved such as abnormal amyloid precursor protein metabolism, cholinergic neuronal dysfunction, and abnormal neuronal membrane phospholipid metabolism. In Alzheimer disease, the most affected areas are the mediotennporal lobes. There are deposits of tau protein in the neurons, which is associated with cellular microtubules in the neurofibrillary tangles. They are outside the neuron deposits of amyloid or aluminosilicate in the neocortex and hippocampus. The symptoms begin with mood and memory changes and then continue with delirium, delusions, and behavioral disturbances. They later cause gait disturbances, pathologic reflexes, and incontinence. Imaging would show diffuse frontotemporal atrophy, widened cortical sulci, and enlarged cerebral ventricles.
Dementia due to Parkinson's disease
is another progressive neurodegenerative disease in which the loss of doparninergic neurons in the substantia nigra causes symptoms such as progressive tremor, postural instability, and bradykinesia. The dementia is seen particularly in slow movements and clIfficulty carrying out executive functions. It is seen in 1 in 1,000 people and dementia is seen in 20% of the cases. Dementia is usually seen in people with an advanced stage of the disease. It should not be confused with the depression that may accompany the disease.
Dementia due to Huntington's disease
is another progressive neurodegenerative disease affecting neurons, but this time the GABA-ergic neurons cause choreoathetosis and dementia. It usually manifests by the age of 40. In the beginning, the person has personality changes and movement disturbances, then later they have slow thinking and problems with doing daily chores. Psychotic features are also common. This disease is associated with an autosomal dominant gene on chromosome 4. Neuroinnaging shows atrophy of the caudate nucleus with ventricular enlargement, or boxcar ventricles.
Dementia due to HIV disease
is caused by the destruction of the brain by the HIV virus. Diffuse multifocal destruction of brain structures occurs, which may lead to dementia in 30% of people with AIDS. Problems walking, hyperreflexia, increased tone and oculomotor deficits, and frontal release signs show motor dysfunction due to brain damage. CNS tumors and opportunistic CNS infections can also cause dementia and need to be ruled out.

Explanation
Dandy-Walker Malformation is characterized by agenesis or hypoplasia of the cerebellar vermis, cystic dilatation of the fourth ventricle, and enlargement of the posterior fossa. Over 700/0 of these patients have associated hydrocephalus, which usually develops postnatally.
Chiari II Malformation is a complex congenital malformation of the brain, nearly always associated with a nnyelomeningocele, that is characterized by downward displacement of the medulla, fourth ventricle, and cerebellum into the cervical spinal canal. Elongation of the pons and fourth ventricle due to a relatively small posterior fossa are also commonly seen.
Alobar holoprosencephaly is the most severe form of the holoprosencephalic defects, which reflect abnormal &vision of the embryonic forebrain. This form of holoprosencephaly consists of a single brain ventricle (monoventricle) without any formation of an interhemispheric fissure (i.e., fused cerebral hemispheres). The falx cerebri, corpus callosum, septum pellucidum, and fornix are absent, and the thalami are fused.
Hydrancephaly is a rare brain malformation in which there is near total absence of cerebral hemispheres and cerebral cortex. It is felt to result from an intra-uterine insult involving the internal carotid arteries bilaterally, and it is associated with a poor prognosis.
Aqueductal stenosis is the most common cause of congenital non-communicating, obstructive hydrocephalus in the newborn. Thinning and stretching of the cortical mantle may be seen as a result of ventricular dilation, which helps to differentiate this condition from hydrancephaly, a condition that lacks a cortical mantle or supratentorial brain formation.

Explanation
Cluster headaches come in groups and may be separated by months or years between attacks. There are 2 types: episodic and chronic. The patient is often a middle-aged man. Cluster headaches are characterized by unilateral excruciating pain (stabbing sensation) often occurring in the ocular, frontal, or temporal areas. These headaches generally last for a period of 15 minutes to 3 hours, recurring at the same time of day. They typically occur during the night. Pain often radiates to the upper teeth, jaw, and neck. The pain is normally accompanied by one or more of the following: ipsilateral conjunctival injection or lacrinnation, ipsilateral nasal congestion or rhinorrhea, ipsilateral eyelid edema, ipsilateral forehead and facial sweating, ipsilateral miosis or ptosis, and a sense of restlessness or agitation. Restlessness is one of the characteristic features of cluster headaches noted in patients. with behaviors such as pacing or rocking the head and trunk with head in hands. Other symptoms of cluster headache include facial flushing or pallor, tenderness on palpation of the ipsilateral carotid artery, bradycardia, and tenderness of the scalp and facial areas. The absence of aura, nausea, or vomiting helps in distinguishing cluster headaches from migraines.
The treatment of choice for acute cluster headaches include the administration of oxygen (7 L per minute for 15 minutes) or sumatriptan, or a combination of both. Other therapeutic measures include intranasal dihydroergotamine, intranasal capsaicin, or intranasal lidocaine. Prednisone and verapamil are often used in prophylaxis.
COMMON MIGRAINE is an intermittent syndrome characterized by hemi-cranial pulsatile cephalic discomfort, including nausea, vomiting, photophobia, anorexia, and phonophobia.
CLASSIC MIGRAINE typically presents with an aura. It also includes features of nausea, vomiting, photophobia, anorexia, phonophobia, and a sense of just wanting to hide in a quiet dark room.
Stress/tension headaches are a generalized type of headache precipitated by stress. They are not one sided. They do not involve photophobia, nausea, vomiting, aura, or phonophobia.
CHRONIC DAILY HEADACHES occur on a daily basis and are often disabling. This type of headache may be challenging to diagnose and treat. Medication overuse, or drug rebound headache, is the most treatable form of refractory daily headache.
A 10-year-old female presents with severe headache and ataxia. Neuroracliologic imaging reveals a cystic tumor in

Explanation
(B) The rapidly progressive dementia in this case is characteristic of Creutzfeldt-Jakob disease (CJD). The dementia is usually accompanied by motor dysfunction and abnormal EEG activity, as described in the question stem. The pathological hallmark of this disease is spongiforrn change in the gray matter. Death usually occurs within 6-12 months of disease onset.
At autopsy, the cerebellum in CJD appears atrophic, not hyperplastic.
Multiple lacunar infarcts are seen with vascular dementia, and patients typically present with focal neurological signs. Additionally, vascular dementia typically presents with a more gradual decline in cognitive function, measured in years rather than months.
Negri bodies are pathognornic for rabies, which does not cause dementia.
Neurofibrillary tangles are often seen in patients with Alzheimer's disease. Alzheimer's disease primarily affects the higher order association cortex; motor dysfunction is not generally observed. Additionally, in Alzheimer's disease, there is a more gradual decline in cognitive function, measured in years rather than months.

Explanation
As the patient has had severe head trauma and has a GCS score of 7 with irregular respirations. The initial therapeutic intervention of choice for reducing the intracranial pressure requires mechanical ventilation. Hypercarbia causes cerebral vasodilatation with increased cerebral blood flow, leading to increased intracranial pressure. Hyperventilation in order to maintain PaCO2 30-35 mmHg is helpful, as it reduces cerebral blood flow through cerebral vasoconstriction, thus reducing intracranial pressure. It is important to monitor the blood gases to ensure adequate oxygenation. PaCO2 of less than 25 mmHg should be avoided, as it may cause cerebral ischemia. Keeping the patient's head in rnidline and elevated 30 degrees allows optimal venous drainage and is further helpful in reducing intracranial pressure.
Intravenous mannitol 20% is an osmotic diuretic and promotes a shift of fluid from the intracellular to the intravascular compartment. In brain injury, irreversible cytotoxic edema occurs due to direct cell injury. Mannitol is less beneficial in the presence of severe disruption of blood brain barrier, as it may enter the central nervous system and draw fluid into the brain, causing exacerbation of cerebral edema. It can produce renal failure and hemolysis, as it creates a very hyperosmolar state. Other side effects include hypovolernia, hypotension, and electrolyte imbalance.
Furosemide is a strong diuretic and can be combined with osmotic diuretics for management of cerebral edema. It is a safer, but less effective, alternative.
Intravenous dexamethasone is not indicated when there is diffuse cerebral injury. It is of benefit when the edema is localized around an intracranial mass, e.g., an abscess or tumor. Corticosteroids have an anti- inflammatory and membrane-stabilizing effect and may be helpful in the management of vasogenic edema associated with mass lesions. Vasogenic edema results when increased permeability of the capillary endothelial cells permits fluid to escape into the extracellular space, but neurones are not primarily injured.
Hypothermia decreases cerebral metabolism and may reduce cerebral blood flow and intracranial pressure. Hypothermia can be achieved by using whole body cooling to a goal core temperature of 32-34 degree Celsius. Mild to moderate cooling has shown a small but significant decrease in mortality and neurological morbidity and an increased risk of pneumonia. Rewarnning should be accomplished in less than 24 hours. However, trials of hypothermia in children with traumatic brain injury showed no improvement in neurological outcome and mortality rates. Rather, mortality was increased in controlled hypothermia group.

Explanation
Graves disease is an idiopathic autoinnmune disorder associated with HLA-38 and HLA-DR3. It is characterized by hyperthyroidism and a diffuse swelling of the thyroid (which moves with deglutition); hence, It also called diffuse toxic goiter.
Hashimoto's thyroiditis and hypothyroidism are associated with lowered levels of thyroxine and its related symptoms, whereas this patient is showing signs of hyperthyroidism. The features that distinguish graves disease from other causes of hyperthyroidism are given below.
Lateral aberrant thyroid is a unique presentation of carcinoma thyroid wherein the lymph node metastasis is detected before the primary.
Commonest clinical features of Hyperthyroidism are: GIT:
• Wt. Loss
• Fatigue
• Anorexia
CARDIORESPIRATORY:
• Dyspnea on exertion
• Palpitations
CNS:
• Emotional lability
• Tumor
• Hyper-reflexa
DERMATOLOGICAL:
• Palnnar erythema
• Alopecia
• Increased sweating
REPRODUCTIVE:
• Amenorrhea / oligomenorrhea
• Infertility
• Impotence
• Decreased libido
OTHER:
• Heat intolerance
• Hyper defecation
• Apathy
Clinical features specific to Graves Disease:
OCULAR:
• Lid lag
• Excess lacrimation
• Chemosis
• Exophthalrnos
• Corneal ulceration
• Diplopia and ophthalmoplegia
• Papilledenna
• Decrease visual acuity
DERMATOLOGICAL:
• Vitiligo
• Clubbing
• Pretibial myxedema
OTHER:
• Lymphadenopathy
• Diffuse goitre with bruit

Explanation
This woman has symptoms of hyperprolactinemia, caused by an adenoma of the lactotroph (an aciclophil). Lactotrophs (mammotrophs) have large, acidophilic granules, a few RER cisternae, and a Goigi apparatus near the nucleus. Lactotrophs are usually found as single cells in the adenohypophysis. In males and nonpregnant females, they are small round or polygonal cells. In lactating females, these cells become much more prominent, due to an expansion of the RER and Golgi apparatus. About 30% of all diagnosed pituitary adenomas are prolactinornas. Physiological hyperprolactinemia occurs during pregnancy, but this has been ruled out by the low B-hCG titer. Head trauma could possibly lead to abnormalities in pituitary function, but this possibility is ruled out by the lack of a history of head trauma.

Explanation
The DSM criteria for alcohol abuse are recurrent use resulting in failure to fulfill obligations, recurrent use in hazardous situations, recurrent legal problems related to use, and continued use despite negative consequences. It is also important to note that the patient has never met the criteria for dependence.
A persistent desire or unsuccessful efforts to cut down is also a symptom of dependence.
Seizures are a symptom of severe withdrawal in chronic alcoholics. When the patient develops withdrawal symptoms and tolerance, requiring larger amount to achieve the desired effect, he or she has met the criteria for dependence.
Suicidal ideation in this patient is a consequence of his depression, which in turn, is secondary to alcohol use. Continued use of a substance despite knowledge of persistent or recurrent physical or psychological problems is also a criterion for dependence.
Tolerance is defined as the need to increase substance use to achieve the desired effect, or as diminished effect with continuous use of the same amount. Tolerance is a major criterion of dependence.

Explanation
This woman is suffering from dementia of the Alzheimer's type. A gradual onset of symptoms, general pervasive memory deficit, difficulties with language, and inability to plan, leading to severe impairment of daily functioning are all characteristic of dementia of the Alzheinner's type.
Amnestic disorder is limited to memory problems, and this woman is demonstrating cognitive dysfunction, such as alterations in language and the loss of the ability to plan.
Pseudodennentia is incorrect since it is a major depressive disorder rather than a dennenting condition. There is no evidence for a depressive syndrome in this patient's presentation.
The diagnosis of substance-induced persisting dementia requires evidence of a history of substance abuse. However, it is the second most likely diagnosis and should be carefully explored with the husband and other close relatives and friends.
Vascular dementia is generally characterized by a step-wise deterioration, not the gradual presentation of this case.

Explanation
A part of aging-related changes is a decrease in the secretion of the growth hormone. It causes a decrease in the muscle mass and an increase in the storage of fat.
Increasing age can be related to the development of Type II diabetes, but would be reflected in his laboratory results.
A decrease in the secretion of the thyroid hormones, which would lead to a decrease in the metabolic rate, should be demonstrated both by clinical presentation and laboratory values.
Paraneoplastic syndrome can take many forms, but is unlikely in a patient with normal physical and laboratory findings.
Although aging can be associated with an altered hypothalamus-pituitary-thyroid function, this is not the case in a patient with normal physical examination and laboratory results.

Explanation
Graves' disease is a type of hyperthyroidism caused by a generalized over-activity of the entire thyroid gland. The patient appears hot and flushed and the thyroid gland enlarges in this condition. It Is believed that Graves' disease is an autoimnnune disorder. Antibodies are produced against certain proteins on the surface of thyroid cells, stimulating those cells to overproduce thyroid hormones. In this condition antibodies are produced against the thyrotropin receptor, thyroglobulin, thyroid peroxidase, and sodium-iodide symporter. The crculating auto- antibodies continuously stimulate the thyroid gland via the thyrotropin receptor. Associated suppression of the pituitary thyrotropin level is due to increased production of thyroid hormones. The onset of the disease is gradual and the symptoms may be mistaken for nervousness due to a stressful life situation. Weight loss occurs followed by other symptoms such as trembling, muscle weakness of the upper arms and thighs, and insomnia. The pituitary gland releases Thyroid Stimulating Hormone (TSH) in response to insufficient levels of thyroid hormone. Communication between the pituitary gland and the thyroid gland through TSH levels controls the levels of thyroid hormone in the blood. If the levels of thyroid hormone are low then the levels of TSH will rise. The measurement of TSH in the blood is taken as a measure of thyroid function. In Graves' disease there is a suppressed level of thyrotropin along with elevated levels of free T4 or T3 hormone levels. The new generation (III generation) assay of TSH is very sensitive and has revolutionized diagnosis of Graves' disease by providing accurate measurements of very low TSH levels. Suppression of TSH is an early and highly sensitive marker of thyrotoxicosis. Estimation of thyroid peroxidase, protein-bound iodine, thyroglobulin, and thyrotropin-releasing hormone are not as reliable as TSH assay.

Explanation
The clinical presentation and laboratory evaluation of this patient suggest the diagnosis of hyperthyroidism secondary to solitary toxic adenoma, which is confirmed by a restricted area of iodine uptake in the right thyroid lobe with suppression of the rest of the gland.
Solitary toxic adenomas
are autonomic nodules that produce thyroid hormone independently of TSH control. They usually evolve from a single cell with a somatic mutation that confers autonomy (TSH-Independence), and as cells multiply, larger amounts of thyroid hormone are produced until hyperthyroidism becomes clinically evident. The diagnosis is suspected when a single nodule is palpable in an otherwise normal thyroid gland in a patient with hyperthyroidism. Diagnosis is confirmed by the finding of a focal area of iodine uptake with varying degrees of suppression of the
rest of the gland. Treatment is directed towards normalization of thyroid hormones by radioiodine treatment, or less frequently, by surgery.
Graves disease
is an autoimmune disorder in which excessive amounts of thyroid hormone are produced due to a constant activation of the TSH receptor in the thyroid cells by stimulating antibodies. Patients present with signs and symptoms of hyperthyroidism (nervousness, irritability, weight loss, tremor, palpitations) and increased diffuse iodine uptake by the gland on radioiodine scanning. Antithyroid antibodies are positive in most patients. Amongst the 3 therapeutic options available to treat Graves disease (antithyroid drugs, radiolodine, surgery), radioiodine is the most preferred in the United States.
Hashimoto thyroiditis
is an autoimmune disease in which diffuse infiltration of lymphocytes is observed in the thyroid, along with some areas of fibrosis. Patients present with varying degrees of hypothyroidism. With time, fibrosis becomes more extensive and the gland becomes atrophic. Occasionally, patients with Hashimoto thyroiditis present with hyperthyroidism in the beginning of the process, when extensive cell damage releases large amounts of thyroid hormone in the circulation. The diagnosis is suggested by a decreased, irregular uptake on radioiodine scan, elevated TSH levels, and positive thyroid antibodies. Replacement with levothyroxine is the treatment for hypothyroidism.
Toxic multinodular goiter
is a condition that affects mostly individuals above 50 years of age, and is a result of areas of autonomy developing in a rnultinodular goiter. Patients present with varying degrees of hyperthyroidism (subclinical and overt) and on radioiodine scan, the thyroid gland is increased in size, with areas of focal increased uptake. The treatment of choice is radioiodine, although surgery is also performed in cases of large, retrosternal goiters.
Thyrotoxicosis factitia
is a condition seen after ingestion of large amounts of thyroid hormone, mainly in psychiatric patients and in individuals who ingest weight loss preparations containing thyroid hormone. Signs and symptoms are similar to those found in patients with endogenous hyperthyroidism. TSH levels are undetectable and free T4 and T3 are elevated. There is absence of radiolodine uptake on scanning and thyroglobulin levels are low, suggesting suppressed endogenous production of thyroid hormones. Severely symptomatic patients may be treated with beta-blockers while the excessive amount of hormones is cleared from the body.

Explanation
The history of neck radiation during her childhood puts this patient at an increased risk for the development of thyroid cancer.
Papillary carcinoma is the most frequently occurring malignancy of the thyroid gland. On histologic examination, psarnmorna bodies and ground glass nuclei ("Orphan Annie eyes") can be seen with papillary thyroid carcinoma. Papillary carcinoma has the best prognosis of the thyroid malignancies.
Thyroid adenoma is a benign tumor; it is not a malignancy of the thyroid.
Follicular carcinoma is the second most frequently occurring thyroid malignancy. On histologic examination, follicles or rudimentary follicles can be seen with follicular carcinoma.
Anaplastic carcinoma occurs much less frequently than papillary carcinoma or follicular carcinoma. On histologic examination, anaplastic carcinoma is undifferentiated. Of the thyroid malignancies, anaplastic carcinoma has the poorest prognosis.
Medullary carcinoma occurs much less frequently than papillary carcinoma or follicular carcinoma. Medullary carcinomas originate from the parafollicular C cells. On histologic examination, medullary carcinoma would demonstrate small round cells.

Explanation
This patient has a pituitary adenoma that is secreting ACTH. Cushing's disease refers to excessive secretion of ACTH by the pituitary. A pituitary adenoma is the most common cause for pituitary hypersecretion of ACTH. The increase in ACTH secretion results in hyperplasia of the adrenal cortex and a subsequent increase in glucocorticoid release. Characteristics of glucocorticoid excess include depression, truncal obesity, purple striae, round face (moon fades), and hypertension.
A distinction exists between Cushing's disease and Cushing's syndrome. Cushing's disease refers specifically to excessive secretion of ACTH by the pituitary. In Cushing's disease, the excessive ACTH secretion by the pituitary results in an increase in glucocorticoid release by the adrenal glands. Cushing's syndrome refers to the effects of excessive glucocorticoids, other than due to pituitary cause. Thus, Cushing's syndrome is due to excessive glucocorticoids. There will be hypertension with both Cushing's disease and Cushing's syndrome.
Addison's disease is primary adrenal insufficiency. The most common cause of Addison's disease is autoinnmunity. Tuberculosis is another cause of Addison's disease. The symptoms seen with Addison's disease include weight loss, lethargy, hyperpigmentation, nausea, and vomiting. Hypotension can be seen. Hyponatremia and hyperkalemia can be seen because of the lack of mineralocorticoicls. When there is decreased stimulation of the adrenal cortex due to a decrease in ACTH, it is called secondary adrenal insufficiency.
Conn's syndrome is due to excessive mineralocorticoids. Conn's syndrome is usually due to an adenoma that is secreting the aldosterone. Conn's syndrome results in hypernatrennia and hypokalennia. There is an associated hydrogen loss as well. There will be hypertension.
Nelson's syndrome is seen in patients who have bilateral adrenalectomy for Cushingrs disease. There is the subsequent development or progression of an ACTH secreting pituitary tumor.

Explanation
The thyroid gland is the first of the body's endocrine glands to develop; it develops on approximately the 24th day of gestation. The gland originates as a proliferation of endodermal epithelial cells on the median surface of the developing pharyngeal floor.
Parathyroid glands begin differentiating at gestational weeks 5-6.
Pineal gland develops in week 10. It appears as a diverticulunn in the diencephalic roof of the third ventricle. However, melatonin cycle is not present on birth; it starts between 49 to 55 post-conception weeks.
The adrenal glands begin development during the fifth gestational week.
The pancreas begins development during the fifth week from dorsal and ventral outgrowths of endoderm that are a part of future duodenum.

Explanation
There are 2 types of hypothyroid, primary and congenital. Secondary hypothyroidism will affect all body systems. The onset is usually over months or years. The lower level of TH (thyroid hormone) is produced by the thyroid gland. Causes of secondary hypothyroidism can include insufficient stimulation of the normal gland, causing TSH (thyroid stimulating hormone) deficiency. There can also be a peripheral resistance to TH.
Clinical manifestations of hypothyroidism can include: confusion, syncope, slowed speech and thinking, memory loss, lethargy, headaches, hearing loss, night blindness, slow, clumsy movements, enlarged pituitary thyrotropes, decreased libido, dyspnea, myxedematous changes in respiratory muscles leading to hypoventilation and carbon dioxide retention, water retention, weight gain, slow movement, dry, flaky skin, dry, brittle, hair, and nnyxedema among other symptoms.
Treatment is based on clinical symptoms, and a decrease in serum T4 and free T4 nearly always is present. TSH concentration increases from loss of negative feedback from thyroid hormone. Hormone replacement therapy is the treatment of choice for hypothyroidism. It is available as a synthetic hormone (levothyroxine or liothyronine).
Hyperparathyroidism is a greater than normal secretion of parathyroid hormone (PTH). The reasons for primary hyperparathyroiclism are classified as either primary or secondary. Primary is a greater than normal secretion of PTH by one or more of the parathyroid glands. The normal feedback mechanisms, such as elevated serum levels of ionized calcium, fail to inhibit PTH secretion by the parathyroid gland. Secondary hyperparathyroidisnn occurs when there is an increase in PTH due to a chronic disease state, including chronic renal failure.
Clinical manifestations are excessive osteoclastic and osteocytic activity, resulting in bone resorption. Outward signs are pathologic fractures, kyphosis of the dorsal spine, and compression fractures of the vertebral bodies. Other symptoms are a greater than 6-month history of hypercalcennia, including kidney stones, hypophosphatemia, hyperchloremia, and increased urinary calcium levels. Treatment includes lowering of severely elevated calcium levels, increasing urinary calcium excretion with diuretics, and long-term management of hypercalcemia by use of drugs that decrease resorptIon of calcium from bone.
Groups of disease with glucose intolerance in common are often called Diabetes Mellitus. There are 2 recognized forms: one that affects obese individuals and another, which is found mainly among the young. The diagnosis of diabetes is based on one of the following: 1- fasting plasma glucose level > 126 mg/dL, 2- glucose value in the 2 hour sample (2hPG) of the standard oral glucose tolerance test (OGTT) of > 200 nng/dL, 3- a plasma glucose level >200 mg/dL anytime during the day, often with the classics symptoms of polydipsia, polyphagia, and polyuria. In Type I, the beta-cells fail, or the cause is idiopathic. In Type II, cells become insulin resistant with Inadequate insulin secretion. Symptoms of Type I are polydipsia, polyuria, polyphagia, weight loss, and fatigue, among others. Symptoms of Type II are often nonspecific. The individual is often over 30, over weight, dyslipidennic, hyperinsulinemic, and hypertensive. The onset tends to be slow and insidious. Other symptoms can include fatigue, pruritus, recurrent Infections, visual changes, or paresthesias.
Treatment for Type I includes control of blood sugars through frequent blood sugar checks and adjusting insulin, diet, and exercise to keep the blood sugars between 70 and 120. Treatment for Type II begins with weight loss, dietary management, and if need be, either oral or insulin medication. In Type II, exercise, in addition to the establishment and maintenance of nutritional therapy, can bring the disease under control.
Cushing Syndrome or Cushing Disease refers to chronic hypercortisolism (excessive levels of circulating cortisol). The usual cause is ectopic ACTH-secretIng tumors, or adrenal-secreting tumors. Signs and symptoms are thinning of scalp hair, faclal flush, moon face, purple striae on the abdomen, truncal obesity, thin extremities, easy bruising, and increased body and facial hair. Treatment is specific for the cause of hypercorticoadrenalism and includes medication, radiation, and surgery.

Explanation
Aging decreases the metabolism of thyroxine and its conversion to triiodothyronine. However, clinically significant alterations of thyroid hormone levels do not occur. Changes in the end-organ response to thyroid hormones are the cause of your patient's clinical presentation.
A decrease in the secretion of the thyroid hormones, which will lead to a decrease in metabolic rate, should be demonstrated in thyroid hormone levels in the blood. However, those levels are normal in your patient.
Paraneoplastic syndrome can take many forms, but is unlikely in a patient with normal physical and laboratory findings.
Although aging can be associated with an altered TSH secretion, this is not the case in your patient. There are no signs of disturbed hypothalamus-hypophysis (thyroid) axis function.
Vasculitis will more likely present with ischemia or multiple organ involvement.

Explanation
MEDULLOBLASTOMA is the most frequently encountered intracranial neuroectodermal tumor in children. Microscopically, medulloblastoma reveals a primitive small-celled malignant tumor forming Homer-Wright rosettes. The nuclei are closely packed, hyperchromatic, relatively uniform and round, oval, or carrot shaped. Dissemination through the CSF is a common complication. The tumor is highly malignant. However, the tumor is very radiosensitive. With total excision and radiation, the 5-year survival rate is as high as 75%.
NEUROBLASTOMA is one of the common solid tumors of childhood and can arise from adrenals or extra-adrenal sites. Cerebellar neuroblastomas are rare, and they arise in the early part of the first decade and show a highly aggressive clinical behavior. The majority are supratentorial, massive, and multicystic. Histologically, they are highly cellular, showing cells that are small with hyperchromatic nuclei and are arranged in solid sheets. A slightly fibrillated matrix traversed by delicate neurites is characteristic. They are negative for GFAP and do not stain with PTAH indicating the absence of glial component. Characteristic Homer-Wright rosettes with tumor cells at the periphery and young nerve fibrils at the center may be present.
CEREBELLAR ASTROCYTOMA predominantly occurs in children. They are characterized by a biphasic pattern. There are bipolar fibrillated and elongated cells packed in bundles with perivascular arrangements and there are stellate cells with short processes with a lacy pattern and show microcystic changes. Also seen are Rosenthal fibers, granular hyaline deposits, and eosinophilic intracytoplasmic bodies. These tumors grow slowly and have a benign course.
OLIGODENDROGLIOMAS constitute about 5 to 15% of gliomas and are most common in the fourth and fifth decades. The lesions are found in cerebral hemispheres, with a predilection for the white matter. Grossly, they are well- circumscribed, gelatinous, often with cyst formation, areas of hemorrhage and calcification. Microscopically, they are characterized by round cells with a small darkly staining nucleus, clear cytoplasm, and clearly defined cell membrane. In general, they have a better prognosis than astrocytomas.
EPENDYMOMAS most often arise next to the ependyma lined ventricular system. They commonly occur near the 4th ventricle in the first 2 decades and in spinal cord in adults. Microscopically, they are characterized by ependymal rosettes, which are duct-like structures with a round or elongated central lumen around which columnar cells are arranged concentrically with basal nuclei.

Explanation
The correct answer is acquired nephrogenic diabetes insipidus. Diabetes insipidus (DI) is a condition of excessive thirst and urination. It may be neurogenic (central) or nephrogenic.
Nephrogenic diabetes insipidus is caused by a resistance to the antidiuretic hormone (ADH) in the kidney. It may be hereditary, which is rare, or acquired. Acquired nephrogenic DI may be caused by lithium toxicity, chronic renal disease, hypercalcemia, etc.
Central DI is characterized by decreased ADH secretion, resulting in the persons' decreased ability to concentrate urine. Causes include tumors of the pituitary, head trauma, and neurosurgery. It may also be idiopathic or familial. Idiopathic central DI is believed to be an autoirnmune condition with destruction of cells in the hypothalamus. Familial central DI is rare.
ADH administration causes an increase in urine osmolality in central DI but not in nephrogenic DI.
A history of lithium use makes acquired nephrogenIc DI more likely than hereditary nephrogenic DI in this patient.

Explanation
Serum hypo-osmolality and serum hyponatremia can be seen with the syndrome of inappropriate ADH secretion (SIADH). The specific gravity of his urine is elevated. The urine is hyperosmotic, which is also consistent with SIADH. This condition can be treated by water restriction. Small cell carcinoma of the lung is a common disease associated with SIADH.
Serum osmolality can be estimated by:
2(NA + K) + urea/2.8 + glucose/18
Note: Sometimes the potassium is ignored in this equation.
The estimate of his serum osnnolality is 250-258 nnOsm/kg. His serum osmolality is low; the normal range is 270- 290 nnOsm/kg. He is hyponatremic, which is the cause of his hypo-osmolality.
Glucose would be found in the urine of a patient with uncontrolled diabetes mellitus. Blood glucose level would be elevated.
Polyuria and polydipsia are associated with diabetes insipidus. The urine would have a low specific gravity and his blood would have an elevated osmolality.
A patient with psychogenic polydipsia also would drink large amounts of water and have a large urine output. Oliguria is defined as scanty urine output.

Explanation
The candidate in this case presents with respiratory symptoms. The clinician requested a chest X-ray to evaluate the patient's lung and mediastinum. The plain X-ray showed the presence of a midline hilar that obviously abuts the bronchi, therefore explaining the irritating dry cough. As for any mass lesion, a biopsy was done. The histologic section shown in the image shows hilar lymph node tissue with multiple granulomas composed of epithelioid histiocytes with occasional giant cells. The increased serum calcium is frequently encountered in granulomatous disease predominantly sarcoidosis.
The next step in the patient's management should entail evaluating the biopsy for mycobacteria and fungi. These organisms are also associated with granulonnatous disease in the lymph nodes and can present with the same symptoms such as the current patient. The acid-fast stain is performed on tissue sections to detect Mycobacterium tuberculosis, which is the etiologic agent of tuberculosis. The silver stain such as Gomori's methenannine silver is frequently used in the lab to detect fungal organisms in tissue sections.
The rationale behind performing these stains on the tissue sections is to rule out the possibility of an infectious granulomatous disease before treating with steroids, which is the therapy of choice in sarcaidosis. However steroids are contraindicated in infectious granulomatous diseases since it mil make the organisms flourish by suppressing the host's immune system. Once the etiology of the granulonnatous disease is unveiled, the treatment with the respective therapeutic regimen can be initiated but not before that. Although some cases of sarcoidosis regress spontaneously, once the disease becomes symptomatic it should be treated. In addition, there are no criteria to aid in identifying the cases that will regress spontaneously versus those that will progress.