1.
A 40-year-old man lived in Central America for a year. Five months into his stay, he experienced a bout of dysentery for which he took some antibiotics. A month later, he noticed fever, tiredness, and pain in the right upper quadrant. A liver scan showed an abscess that was associated with elevated blood levels of liver enzymes. How did this disease develop?
Correct Answer
A. Motile tropHozoites from the colon invaded the liver
Explanation
The correct answer is "Motile trophozoites from the colon invaded the liver." In this scenario, the man experienced dysentery, which is often caused by an infection with the parasite Entamoeba histolytica. The motile trophozoites of this parasite can invade the liver, leading to the formation of an abscess. The presence of elevated liver enzymes in the blood further supports the diagnosis of liver involvement.
2.
You are the principal investigator in an HIV-1 prevalence study. In the course of the study in a high-risk group, a week’s worth of sera is screened in the laboratory by ELISA. Serum samples yielding a positive result are then re-tested by western blot analysis for confirmation. The following results are obtained:
Which samples are indicative of HIV-1 infection?
Correct Answer
C. I, II, III, IV, and V
Explanation
Interpretation:
– Negative result: Total absence
of bands associated with HIV-1
(CDC guidelines); According to
the WHO guidelines, a very weak
p17 band would also qualify as a
negative result
– Positive result: Presence of at
least 2 of the following bands
(CDC guidelines):
• p24
• gp41
• gp120/160
3.
A 39-year-old jaundiced man with icteric sclerae has a slightly elevated total serum bilirubin (85% indirect), increased urinary hemoglobin, and hemosiderin. Which of the following is the most likely diagnosis?
Correct Answer
B. Intravascular hemolysis
Explanation
The most likely diagnosis in this case is intravascular hemolysis. The patient's presentation of jaundice, icteric sclerae, elevated total serum bilirubin (with a high percentage of indirect bilirubin), increased urinary hemoglobin, and hemosiderin are consistent with intravascular hemolysis. Intravascular hemolysis refers to the destruction of red blood cells within the bloodstream, leading to the release of hemoglobin and subsequent elevation of bilirubin levels. This can be caused by various conditions such as autoimmune hemolytic anemia, paroxysmal nocturnal hemoglobinuria, or mechanical heart valves.
4.
A 16-year-old jaundiced girl is scheduled for splenectomy because of splenomegaly and anemia. Her peripheral blood smear shows a normochromic normocytic anemia of PBS. Her Direct Coombs' test is negative, and osmotic fragility of the red cells is increased. What type of RBCs would most likely be seen of PBS?
Correct Answer
B. SpHerocytes
Explanation
The correct answer is spherocytes. Spherocytes are small, round red blood cells that lack central pallor. They are commonly seen in conditions such as hereditary spherocytosis, autoimmune hemolytic anemia, and certain drug-induced hemolytic anemias. In this case, the patient's peripheral blood smear shows normochromic normocytic anemia, which is consistent with spherocytes. The negative Direct Coombs' test and increased osmotic fragility of the red cells further support the diagnosis of hereditary spherocytosis, a condition characterized by the presence of spherocytes.
5.
An autopsy findings from a 65-year-old man revealed a left and right ventricular hypertrophy, nutmeg liver, pulmonary & pedal edema. Which of the following is the most likely cause of death?
Correct Answer
C. Congestive Heart Failure
Explanation
http://upload.wikimedia.org/wikipedia/commons/thumb/f/fc/Congestive_hepatopathy_high_mag.jpg/640px-Congestive_hepatopathy_high_mag.jpg
In hepatology, congestive hepatopathy, also known as nutmeg liver and chronic passive congestion of the liver, is liver dysfunction due to venous congestion, usually cardiac dysfunction, i.e. right heart failure or (less specifically) congestive heart failure. The gross pathological appearance of a liver affected by chronic passive congestion is "speckled" like a grated nutmeg kernel; the dark spots represent the dilated and congested hepatic venules and small hepatic veins. The paler areas are unaffected surrounding liver tissue. When severe and longstanding, hepatic congestion can lead to fibrosis, which is often called cardiac cirrhosis Increased pressure in the sublobular branches of the hepatic veins causes an engorgement of venous blood, and is most frequently due to chronic cardiac lesions, especially those affecting the right heart, the blood being dammed back in the inferior vena cava and hepatic veins. Central regions of the hepatic lobules are red/brown and stand out against the noncongested, tan-coloured liver. Centrilobular necrosis occurs. Macroscopically, the liver has a pale and spotty appearance in affected areas, as stasis of the blood causes pericentral hepatocytes (liver cells surrounding the periportal venules of the liver) to become deoxygenated compared to the relatively better-oxygenated periportal hepatocytes adjacent to the hepatic arterioles. This retardation of the blood also occurs in pulmonary lesions, such as chronic interstitial pneumonia, pleural effusions, and intrathoracic tumors.
6.
A patient is given a mismatch ABO transfusion because of a clerical error. The patient complains of kidney pain and hematuria. Which of the following types of hypersensitivity reaction is most likely?
Correct Answer
B. Type II
Explanation
In a Type II hypersensitivity reaction, the immune system mistakenly attacks healthy cells or tissues. In this case, the patient received a mismatched ABO transfusion, leading to the immune system targeting and destroying the transfused red blood cells. The kidney pain and hematuria are likely due to the destruction of red blood cells in the kidneys, causing inflammation and damage. This aligns with a Type II hypersensitivity reaction, making it the most likely explanation for the patient's symptoms.
7.
You are asked to review lab results shown below. Which of the following antibodies would be most helpful in confirming your diagnosis?
Correct Answer
E. Antibodies against ds-DNA
Explanation
Antibodies against ds-DNA would be most helpful in confirming the diagnosis because the presence of these antibodies is strongly associated with systemic lupus erythematosus (SLE), an autoimmune disease. SLE is characterized by the production of autoantibodies against various components of the cell nucleus, including ds-DNA. Therefore, the presence of antibodies against ds-DNA can support the diagnosis of SLE.
8.
A 56-year-old Caucasian farmer presented with an ulcerated, erythematous lesion on the dorsum of his right and enlarged ipsilateral axillary lymph nodes. The lesion was biopsied. The gross and microscopic appearance of the mass is shown for your evaluation. Which of the following is the most likely underlying molecular mechanism of the described neoplasm?
Correct Answer
C. Formation of pyrimidine dimers
Explanation
Pyrimidine dimers are the primary cause of melanomas in human beings.
Pyrimidine dimers are molecular lesions formed from thymine or cytosine bases in DNA via photochemical reactions. Ultraviolet light induces the formation of covalent linkages by reactions localized on the C=C double bonds. In dsRNA, uracil dimers may also accumulate as a result of UV radiation. Two common UV products are cyclobutane pyrimidine dimers (CPDs, including thymine dimers) and 6,4 photoproducts. These premutagenic lesions alter the structure of DNA and consequently inhibit polymerases and arrest replication. Dimers may be repaired by photoreactivation or nucleotide excision repair, but unrepaired dimers are mutagenic.
9.
A 44-year-old Indian American female visits her family physician for routine check up. During vaginal examination the physician finds the uterine cervix abnormalities shown for your evaluation. A subsequent cervical biopsy detects a single group of several evidently malignant cells that spreads into the dermis through the basement membrane. Which of the following is the most likely prognosis?
Correct Answer
D. Microinvasive carcinoma
Explanation
http://upload.wikimedia.org/wikipedia/commons/c/c3/In_situ_carcinoma.jpgCarcinoma in situ (CIS) is an early form of cancer that is defined by the absence of invasion of tumor cells into the surrounding tissue, usually before penetration through the basement membrane. In other words, the neoplastic cells proliferate in their normal habitat, hence the name "in situ" (Latin for "in its place"). For example, carcinoma in situ of the skin, also called Bowen's disease, is the accumulation of neoplastic epidermal cells within the epidermis only, that has failed to penetrate into the deeper dermis. For this reason, CIS will usually not form a tumor. Rather, the lesion is flat (in the skin, cervix, etc.) or follows the existing architecture of the organ (in the breast, lung, etc.). Some CIS, however, do form tumors, such as in the colon (polyps), in the bladder (pre-invasive papillary cancer), or in the breast (more properly called ductal carcinoma in situ). Many forms of invasive carcinoma (the most common form of cancer) originate after progression of a CIS lesion. Therefore, CIS is considered a precursor or incipient form of cancer that may, if left untreated long enough, transform into a malignant neoplasm.
10.
A 38-year-old HIV-positive African American female has CD4+ count of 90/microliter. Which of the following is the LEAST likely tumor that can arise in this woman?
Correct Answer
B. Breast carcinoma
Explanation
HIV infection and a low CD4+ count are associated with an increased risk of developing certain types of cancers, such as Kaposi sarcoma, uterine cervix carcinoma, and B-cell lymphoma. However, breast carcinoma is less commonly associated with HIV infection and a low CD4+ count compared to the other options. Therefore, breast carcinoma is the least likely tumor to arise in this woman.
11.
A 51-year-old Caucasian male presents with soft tissue sarcomas, breast cancer, brain tumor, and adrenal cortex tumors. Which of the following carcinogenic mechanisms is most likely implicated in the development of the patient’s disease?
Correct Answer
A. LOH of p53 gene
Explanation
The patient's presentation with multiple types of cancer suggests a genetic predisposition to cancer development. LOH (loss of heterozygosity) of the p53 gene is a known mechanism that can lead to the development of various types of cancer. The p53 gene is a tumor suppressor gene that plays a crucial role in regulating cell growth and preventing the formation of tumors. LOH of the p53 gene can result in the loss or inactivation of one copy of the gene, leading to an increased risk of cancer development.
12.
A 37-year-old African American male, a jazz singer presents with hoarseness of voice. He reports a 25-pack-year history of smoking. Laryngoscopy reveals an area of papillomatous growth (shown) and biopsy is taken. Histological examination of the biopsy reveals fibro-capillary stalks covered by proliferating squamous epithelium with preserved polarity and mild cellular atypia; neither mitotic figures nor penetration through the basement membrane are seen. Which of the following is the most likely diagnosis?
Correct Answer
A. Squamous cell papilloma
Explanation
The most likely diagnosis in this case is squamous cell papilloma. This is supported by the histological examination findings of fibro-capillary stalks covered by proliferating squamous epithelium with preserved polarity and mild cellular atypia. Squamous cell papilloma is a benign tumor that commonly occurs in the larynx and is associated with smoking. It is characterized by the presence of papillomatous growths, which are consistent with the findings on laryngoscopy. The absence of mitotic figures and penetration through the basement membrane further support the benign nature of the lesion.
13.
An 18-month old with a history of recurrent bacterial and viral infections, failure to thrive, developmental delay, and tremors is submitted to your care. On exam you notice a lack of peripheral lymphoid tissue. Blood analysis reveals lymphopenia with normal B cell count and normal immunoglobulin levels. Patient is most likely suffering from which of the following?
Correct Answer
C. Purine nucleoside pHospHorylase
Explanation
Purine nucleoside phosphorylase deficiency, often called PNP-deficiency, is a rare autosomal recessive metabolic disorder which results in severe combined immunodeficiency.
In addition to the symptoms associated with immunodeficiency, such as depletion of T-cells, decline of lymphocyte activity, and an abrupt proliferation of both benign and opportunistic infections, PNP-deficiency is often characterized by the development of autoimmune disorders. Lupus-erythematosis, autoimmune hemolytic anemia, and idiopathic thrombocytopenic purpura have been reported with PNP-deficiency
PNP-deficiency is extremely rare. Only 33 patients with the disorder in the United States have been documented.
In the United Kingdom only one child has been diagnosed with this disorder.......classic Buxbaum
14.
You are a neonatologist working in a tertiary care hospital in a state capital. A 4-week old male is transferred to you with severe jaundice that appeared at birth and has been worsening ever since. The boy is the first child of a healthy Jewish couple; pregnancy and vaginal delivery were unremarkable. The boy is of average height and weight for his age, in no acute distress, but shows marked jaundice and slight hepatomegaly. Lab: CBC normal, indirect bilirubin high, low fecal urobilinogen.
What is the most likely diagnosis?
Correct Answer
A. Uridyl glucuronyl transferase deficiency
Explanation
The most likely diagnosis in this case is uridyl glucuronyl transferase deficiency. This is indicated by the severe jaundice that appeared at birth and has been worsening, along with the high indirect bilirubin and low fecal urobilinogen levels. Uridyl glucuronyl transferase deficiency, also known as Gilbert syndrome, is a genetic disorder that affects the liver's ability to process bilirubin, leading to an accumulation of bilirubin in the blood and resulting in jaundice. The patient's normal CBC and lack of acute distress also support this diagnosis.
15.
A physician suspected, and the supporting lab results indicated, that his patient’s diagnosis was diffuse intrinsic brain stem glioma. The patient’s prognosis was extremely poor. The doctor needed to present his findings to the patient. The most appropriate delivery of the news to the patient is in keeping with which of the following accurate statements?
Correct Answer
D. pHysicians clarify what can be realistically expected and distinguish this from what might be wished for, or what is most feared.
Explanation
Physicians clarify what can be realistically expected and distinguish this from what might be wished for, or what is most feared. This is the most appropriate way to deliver the news to the patient because it allows the physician to provide an honest and accurate assessment of the patient's prognosis while also addressing any hopes or fears the patient may have. It ensures that the patient is fully informed and able to make decisions based on realistic expectations.
16.
At his most recent routine checkup, a 34-year-old man infected with HIV-1 displays a decrease in his CD4 count and an increase in his viral load. The patient has been on a HAART regimen for the past year that includes the drug maraviroc. Molecular diagnostics reveal that the patient’s viral strain is now displaying significant resistance to maraviroc. Which of the following most likely identifies the mechanism behind this development of viral resistance?
Correct Answer
A. Shift to a CCR5-CXCR4 dual-tropism
Explanation
The most likely mechanism behind the development of viral resistance to maraviroc in this patient is a shift to a CCR5-CXCR4 dual-tropism. This means that the patient's viral strain has evolved to use both the CCR5 and CXCR4 co-receptors to enter host cells, instead of solely relying on the CCR5 co-receptor. Maraviroc specifically targets the CCR5 co-receptor, so a shift to dual-tropism would render the drug less effective. This shift in tropism is a common mechanism of resistance to maraviroc.
17.
Early one morning, a 50-year-old male patient in a skilled nursing unit, complains that he has a sharp pain in his chest, and he cannot get enough breath. He recently underwent amputation of his foot and is completing an IV antibiotic therapy for a gangrenous chronic wound infection associated with diabetic neuropathy. He is receiving unfractionated heparin subcutaneously for DVT prophylaxis. He denies nausea, vomiting or dizziness but complains about a non-productive cough. His vital signs: BP 132/66; RR 21; T36.5. His cardiovascular system showed regular rate and rhythm and no abnormalities.
Laboratory investigations showed:
Normal cardiac enzymes
Hgb 14g/dL
Hct40%
Platelets 61x100/mm3
WBC 8x100/mm3.
A ventilation-perfusion lung scan showed multiple segmental perfusion defects. Which anticoagulant agent would be most appropriate to initiate anticoagulation for treatment of this patient’s condition?
Correct Answer
E. Lepirudin
Explanation
Lepirudin may be used as an anticoagulant when heparins (unfractionated or low-molecular-weight) are contraindicated because of heparin-induced thrombocytopenia.
Lepirudin is a recombinant hirudin[1] derived from yeast cells. It is almost identical to hirudin extracted from Hirudo medicinalis. It differs by the substitution of leucine for isoleucine at the N-terminal end of the molecule and the absence of a sulfate group on the tyrosine at position 63.
Baxter Healthcare Corporation has announced that it will cease the production of lepirudin
Brand name: Refludan, Generic: Lepirudin rDNA for injection.
18.
Six young medical students come to the University Health Centre complaining of diarrhea which is pale, greasy and malodorous, with abdominal cramping, gas, and pain. They spent the weekend in a camping site in the mountains and drank untreated stream water. A preliminary diagnosis of malabsorbtion diarrhea was given. Trophozoites were detected in fecal samples by identification of the protozoan antigen using counterimmunoelectrophoresis. Which of the following antiprotozoal drugs would be the most appropriate therapy?
Correct Answer
B. Metronidazole
Explanation
These young men have Beaver Fever....NO, John, not that kind of beaver.
This is Giardia, which you get from drinking water from a stream in the woods, hence "beaver fever"
THe give away is FOUL SMELLING (malodorous) and gaseous diarrhea.
Tropozites are seen in the stool with Giardiasis.
metronidazole (Flagyl) is the treatment of choice.
remember to warn your patient to avoid alcohol while on flagyl. (aldehyde dehydrogenase reaction)
19.
A 58-year-old man presented to the renal transplant clinic complaining that he had unremitting diarrhea for 3 days. Two months ago he had a cadaveric kidney transplant. In addition to other medications such as gancyclovir, sulfamethoxazole/trimethoprim, the patient is taking immunosuppressive therapy which includes-tacrolimus, prednisone, and mycophenolate mofetil.
Selected lab results show:
Serum creatinine 1.7mg/dL (0.2-1.0mg/dL)
K+: 5.7meq/L
Fasting blood sugar: 188mg/dL
Which one of his medications is most likely to be responsible for these lab findings?
Correct Answer
D. Tacrolimus
Explanation
Side effects can be severe and include infection, cardiac damage, hypertension, blurred vision, liver and kidney problems (tacrolimus nephrotoxicity), hyperkalemia, hypomagnesemia, hyperglycemia, diabetes mellitus, itching, lung damage (sirolimus also causes lung damage), and various neuropsychiatric problems such as loss of appetite, insomnia, Posterior reversible encephalopathy syndrome, confusion, weakness, depression, cramps, neuropathy, seizures, tremors, and catatonia.
In addition it may potentially increase the severity of existing fungal or infectious conditions such as herpes zoster or polyoma viral infections.