1.
A 23-year-old woman presents to her physician with a lump in her left breast. She has no family history of cancer and is taking low-dose oral contraceptives. On examination, she has a 2-cm rubbery, round, freely mobile mass. An ultrasound is performed showing a solid mass. Core needle biopsy is reported as a fibroadenoma. Which of the following characteristics was most likely seen on the sample?
Correct Answer
C. Cellular hyperplasia with glandular architecture
Explanation
Concept: Diagnosis of benign tumor based on histopathology findings Fibroadenomas of the breast, are lumps composed of fibrous and glandular tissue. Because breast cancer can also appear as a lump, doctors may recommend a tissue sample (biopsy) to rule out cancer in older patients. Unlike typical lumps from breast cancer, fibroadenomas are easy to move, with clearly defined edges. Fibroadenomas are sometimes called breast mice or a breast mouse owing to their high mobility in the breast A fibroadenoma is usually diagnosed through clinical examination, ultrasound or mammography, and often a NEEDLE BIOPSY sample of the lump Cytology: The diagnostic findings on needle biopsy consist of abundant stromal cells, which appear as bare bipolar nuclei, throughout the aspirate; sheets of fairly uniform-size epithelial cells that are typically arranged in either an antler-like pattern or a honeycomb pattern. These epithelial sheets tend to show typical metachromatic blue staining on DiffQuick staining. Foam cells and apocrine cells may also be seen, although these are less diagnostic features.
2.
A 21-year-old woman presents with a painful right knee. An x-ray reveals a mass arising from the distal femur. Biopsy shows a malignant tumor arising from the bone, osteosarcoma; the malignant tumor cells laying down osteoid. When the patient was 2 years old, a cancerous lesion was surgically removed from the right eye. Which of the following regulatory genes is most likely responsible for these eye and bone lesions?
Correct Answer
C. RB suppressor gene
Explanation
Concept: Association of RB tumor suppressor gene with cancers
3.
A 48-year-old man presents to the emergency room complaining of vague abdominal pain, intermittent fevers, and a 9-kg (20-lb) weight loss over the past 4 months. On physical examination, he has diffuse abdominal tenderness, hepatomegaly, and yellow sclera. CT-guided liver biopsy reveals hepatocellular carcinoma. Which of the following tumor markers is useful for monitoring the recurrence of disease following surgery in this patient?
Correct Answer
B. AFP
Explanation
Concept: Use of serum tumor markers for monitoring hepatocellular carcinoma AFP: A level above 500 nanograms/milliliter of AFP in adults can be indicative of hepatocellular carcinoma, germ cell tumors, and metastatic cancers of the liver. Elevation of AFP is used as one factor in the diagnosis of ataxia-telangiectasia AFP is measured in pregnant women through the analysis of maternal blood or amniotic fluid, as a screening test for a subset of developmental abnormalities: it is principally increased in open neural tube defects and omphalocele and is decreased in Down syndrome. It can also be used as a biomarker to detect a subset of tumors in non-pregnant women, men, and children.
4.
A 10-month-old infant is taken to the doctor for persistent jaundice and easy fatigability. Laboratory studies are ordered and a peripheral smear shows the presence of spherocytes. Which of the following characteristics would be seen in hereditary spherocytosis?
Correct Answer
A. Increased osmotic fragility
Explanation
Spherocytes (the spherical red blood cells that give spherocytosis its name) are less able to withstand hypotonic solutions and will burst, even in salinities that are relatively close to blood. This is partly because the red blood cell membranes are weaker, but also because the cells are already spherical and so can not increase their volume by changing shape, unlike the normal biconcave red blood cells. The Ham test is a test used in the diagnosis of paroxysmal nocturnal hemoglobinuria Heinz bodies are formed by damage to the hemoglobin component molecules, usually through oxidant damage, or from an inherited mutation (i.e. change of an internal amino acid residue). As a result, an electron from the hemoglobin is transferred to an oxygen molecule, which creates a Reactive Oxygen Species (ROS) that can cause severe cell damage leading to premature cell lysis. Damaged cells are cleared by macrophages in the spleen, where the precipitate and damaged membrane are removed, leading to characteristic "Bite cells". The denaturing process is irreversible and the continual elimination of damaged cells leads to Heinz body anemia.
5.
A mother came to the pediatric clinic with her one-year-old child, who appeared pale. Physical examination revealed frontal bossing and splenomegaly. A complete blood count showed anemia. Peripheral blood smear revealed microcytic hypochromic red cells and many target cells. A radiograph of the skull showed a “hair on end” appearance. Based on the information provided, which of the following laboratory findings is most closely associated with this patient’s clinical condition?
Correct Answer
B. Increase in HbF on electropHoresis
Explanation
Concept: Thalassemia – Association between clinical features and laboratory findings Pt has a severe B-thalassemia. This will lead to a loss of iron, resulting in an iron def anemia. (microcytic hypochromic). the body will try to compensate with EMH. this will lead to the skeletal changes we see in this pt and the elevated HbF. Splenomegaly is from the Extravascular destruction of the RBC's. Remember also that in Sickel cell, Hydroxyurea is given to increase HbF, which helps with symptoms.
6.
A bone marrow aspirate revealed a hypercellular marrow with 40% blasts. The blasts were positive for myeloperoxidase and Sudan Black B; and negative for PAS stain. Flow cytometry revealed positivity for CD13 and CD33. What would be your diagnosis on the basis of all these findings?
Correct Answer
E. Acute myeloid leukemia
Explanation
CD33 is the target of gemtuzumab ozogamicin, a monoclonal antibody-based treatment for acute myeloid leukemia. Cytochemical stains on blood and bone marrow smears are helpful in the distinction of AML from ALL, and in the subclassification of AML. The combination of a myeloperoxidase or Sudan black stain and a nonspecific esterase stain will provide the desired information in most cases. The myeloperoxidase or Sudan black reactions are most useful in establishing the identity of AML and distinguishing it from ALL. The nonspecific esterase stain is used to identify a monocytic component in AMLs and to distinguish a poorly differentiated monoblastic leukemia from ALL. The diagnosis and classification of AML can be challenging, and should be performed by a qualified hematopathologist or hematologist. In straightforward cases, the presence of certain morphologic features (such as Auer rods) or specific flow cytometry results can distinguish AML from other leukemias; however, in the absence of such features, diagnosis may be more difficult. The French–American–British (FAB) classification requires a BLAST PERCENTAGE of at least 30% in bone marrow (BM) or peripheral blood (PB) for the diagnosis of AML Myeloperoxidase (MPO) is a peroxidase enzyme that in humans is encoded by the MPO gene. Myeloperoxidase is most abundantly expressed in neutrophil granulocytes (a subtype of white blood cells). It is a lysosomal protein stored in azurophilic granules of the neutrophil. MPO has a heme pigment, which causes its green color in secretions rich in neutrophils, such as pus and some forms of mucus. PAS staining is mainly used for staining structures containing a high proportion of carbohydrate macromolecules (glycogen, glycoprotein, proteoglycans), typically found in e.g. connective tissues, mucus, the glycocalyx, and basal laminae.
7.
A 45-year-old man comes to your office complaining of blood in his sputum and urine. Physical examination reveals a man with hypertension, respiratory distress, and edema. Urinalysis shows the presence of red blood cells and proteins in the urine. What type of hypersensitivity reaction is most likely associated with this patient’s diagnosis?
Correct Answer
B. Type II
Explanation
This patient's symptoms and findings suggest a type II hypersensitivity reaction. Type II hypersensitivity reactions involve the formation of antibodies against specific cells or tissues. In this case, the presence of red blood cells and proteins in the urine suggests an autoimmune response targeting these cells. The hypertension, respiratory distress, and edema may be due to damage to blood vessels caused by the immune response.
8.
A 55-year-old woman presents with dysphagia, diarrhea, and weight loss. Physical examination reveals a woman who appears younger than her stated age with abnormal breath sounds. Lab data is significant for antibodies against DNA topoisomerase I. What is the most likely diagnosis?
Correct Answer
A. Systemic sclerosis
Explanation
The most likely diagnosis in this case is systemic sclerosis. Systemic sclerosis is a chronic autoimmune disease characterized by fibrosis and vascular abnormalities. The patient's symptoms of dysphagia, diarrhea, and weight loss are consistent with gastrointestinal involvement, which is common in systemic sclerosis. The presence of antibodies against DNA topoisomerase I, also known as Scl-70, is highly specific for systemic sclerosis. The abnormal breath sounds may be indicative of pulmonary involvement, another common feature of this disease. Sjogren's syndrome, CREST syndrome, systemic lupus erythematosus, and discoid lupus are all autoimmune diseases, but they are less likely to present with the combination of symptoms and laboratory findings described in this case.
9.
A 63-year-old man with diabetes mellitus and previous history of hypertension and M.I. presents to the clinic because of difficulty breathing while walking 25 yards on his lawn. He also requires 3-4 pillows to sleep at night. On physical examination, there are bibasilar crackles and pitting edema of lower extremities. Also, there is pressure in the right upper quadrant of the abdomen and distension of the right internal jugular vein is noted. Which of the following is the most likely pathophysiological mechanism of the manifestations in this patient’s lung?
Correct Answer
E. Increased intravascular (hydrostatic) pressure
Explanation
The patient's symptoms of difficulty breathing, pitting edema, and distension of the right internal jugular vein are consistent with congestive heart failure (CHF). In CHF, there is impaired pumping function of the heart, leading to increased intravascular (hydrostatic) pressure. This increased pressure causes fluid to leak out of the vessels and into the surrounding tissues, resulting in pulmonary congestion, edema, and jugular vein distension. The other options are not associated with these specific manifestations seen in CHF.
10.
Dr. Richards has learned from a 2001 Swedish study that 25% of all the parents said their intellectual awareness of their child's impending death came less than 24 hours before the death happened. 45% said their emotional awareness came less than 24 hours before the child's death. The researchers also found that adequate information from the doctor on the child's fatal prognosis was the main predictor of intellectual and emotional awareness. According to this study, which of the following “SPIKES” components is best designed to reduce the chances that parents are unprepared emotionally and intellectually for dealing with their child’s illness?
Correct Answer
A. Knowledge
Explanation
The correct answer is "Knowledge". According to the given information, the study found that adequate information from the doctor on the child's fatal prognosis was the main predictor of intellectual and emotional awareness. Therefore, providing knowledge to parents about their child's illness and prognosis would reduce the chances of them being unprepared emotionally and intellectually.
11.
A 30-year-old woman is worked up for an abnormal Pap smear. Colposcopy shows lesions in the cervix indicative of a malignancy caused by Papillomavirus infection.
Which of the following is the most likely process of transformation?
Correct Answer
C. Binding protein E7 to Rb and bypassing cell cycle control
Explanation
The most likely process of transformation in this case is the binding of protein E7 to Rb and bypassing cell cycle control. This is because the question mentions that the lesions in the cervix are indicative of a malignancy caused by Papillomavirus infection. The E7 protein of Papillomavirus is known to bind to the retinoblastoma protein (Rb) and inactivate it, leading to uncontrolled cell growth and proliferation. This disruption of the cell cycle control is a key step in the development of cervical cancer.
12.
Organ grafts between genetically identical individuals such as identical twins are characterized by the following statement:
Correct Answer
A. Not rejected even with no immunosuppression
Explanation
Organ grafts between genetically identical individuals, such as identical twins, are not rejected even with no immunosuppression because their immune systems recognize the transplanted organ as "self" and do not mount an immune response against it. This is because genetically identical individuals have the same major histocompatibility complex (MHC) molecules, which are responsible for presenting antigens to the immune system. As a result, there is no need for immunosuppressive drugs to prevent rejection of the transplanted organ.
13.
A vaccine that is intended to specifically prevent the infection of human erythrocytes by malaria parasite must be directed against what stage of the organism’s life cycle?
Correct Answer
B. Sporozoite
Explanation
from concept sheet of mini 2 (jan 2012)
H_MI: Rationale for a malaria vaccine against sporozoites (Adebyi)
Scenario: they were creating a vaccine that would be most effective. And the most effective vaccine is works when the malaria mosquito first bites you, what does the vacine target?
Vaccine against the sporozites
14.
A medical student on a community medicine posting discovered that the people living in an isolated area had no access to potable water and had been drinking untreated water from a pond that was infested with Cyclops (a water flea). Which infectious disease had they been most likely exposed to?
Correct Answer
A. Dracunculiasis
Explanation
Dracula "flees" from Holy "water"
15.
K.L. was born in Ville de Saguenay (Quebec), birth was uneventful. However, she failed to thrive. Suddenly at the age of 5 months, her condition deteriorated rapidly and she was transferred to an emergency room. Glutamic: pyruvic transaminase (GPT), aspartate aminotransferase (AST), ammonia, and creatinine levels in blood were elevated; attending physicians noticed a strong cabbage-like smell originating from her. The most likely diagnosis is
Correct Answer
A. Tyrosinemia I
Explanation
The symptoms described in the question, including failure to thrive, elevated levels of GPT, AST, ammonia, and creatinine in the blood, and a strong cabbage-like smell, are consistent with the diagnosis of Tyrosinemia I. Tyrosinemia I is a rare genetic disorder that affects the breakdown of the amino acid tyrosine. It results in the accumulation of toxic substances in the body, leading to liver and kidney damage. The elevated levels of GPT and AST indicate liver dysfunction, while the elevated ammonia and creatinine levels suggest kidney dysfunction. The strong cabbage-like smell is a characteristic odor associated with tyrosinemia.
16.
A 24-year-old man was sent by his physician to the warfarin investigatory clinic because his doctor was worried by the patient’s unstable INR values. He had recently developed atrial fibrillation for which he was prescribed warfarin. At the clinic, his INR values were > 4. Genetic analysis of his CYP2 9 enzyme was ordered and it showed that the patient had a CYP variant of 2C9 which had significantly reduced activity in the liver. What was the most likely explanation for this patient’s INR values?
Correct Answer
E. Increased prothrombin time due to increased blood warfarin levels
Explanation
The patient in this scenario has a CYP2C9 variant with significantly reduced activity in the liver. CYP2C9 is responsible for metabolizing warfarin, a commonly used anticoagulant. With reduced CYP2C9 activity, the patient's liver is unable to efficiently metabolize warfarin, resulting in increased blood levels of the drug. Warfarin works by inhibiting the synthesis of vitamin K-dependent clotting factors, including prothrombin. Therefore, increased blood warfarin levels would lead to an increased prothrombin time, indicating a longer time for clot formation.
17.
A 25-year-old student is about to leave for sub-Sahara Africa on a short-term research program on drug resistance. He was given mefloquine as a prophylactic measure because falciparum malaria was endemic and chloroquine resistance was widespread in the area he was visiting. Which of the following mechanisms of resistance to drugs by the plasmodial cell, common to tumor cells, bacteria, and fungi, would be the most likely line of his research?
Correct Answer
A. Enhanced efflux transporter molecules
Explanation
The most likely line of research for the student would be studying the mechanism of enhanced efflux transporter molecules in the plasmodial cell. This mechanism is common to tumor cells, bacteria, and fungi, and it allows the cells to pump out drugs and prevent them from accumulating inside the cell. By studying this mechanism, the student can understand how the plasmodial cell is able to resist the effects of mefloquine and develop strategies to overcome this resistance.
18.
A patient, who received a renal transplant six months previously, is being maintained on methylprednisolone, sirolimus, and mycophenolate mofetil. A week ago he was brought to the ER with a fever, pain over the graft, and he reported a significant decrease in urine volume. A panel of tests and a renal biopsy were ordered. The results of tests on his blood revealed creatinine levels of 3.8/dL (normal 0.5-1.2mg/dL), BUN 56mg/dL (normal 5-20) ; the BUN /creatinine ratio is 14/1(normal 10/1). Which of the following best reflects the most appropriate modification to the current course of therapy for this patient?
Correct Answer
C. Add muromonab CD3
Explanation
Muromonab CD3 is an immunosuppressive medication that is used to treat acute rejection in renal transplant patients. The patient in this case is presenting with symptoms suggestive of graft dysfunction, such as fever, pain over the graft, and decreased urine volume. The elevated creatinine and BUN levels further support the possibility of acute rejection. Therefore, adding muromonab CD3 would be the most appropriate modification to the current course of therapy for this patient.