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usmle step 1 pathology question bank 2
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u world question bank questions for pathology
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1. A 56-year-old manager of a small firm presents to the clinic withprogressive fatigue and occasional heart palpitations over the last
six months. She states that she has been under a lot of stress
recently due to some problems at work. She has also been eating
out frequently and admits to drinking two to three cans of beer on
the weekends. Her blood haemoglobin level is 8.5 g/dl, and the
peripheral blood smear reveals pale microcytes. The initial
evaluation of this patient should be focused on identifying which of
the following?
A. Poor nutrition
B. Blood loss
C. Hemolysis
D. Hematologic malignancy
E. Liver disease
F. Drug abuse
Answer: B
Explanation:
The fatigue and heart palpitations reported by this patient are common
manifestations of all anemias. Her laboratory findings, however, indicate
she has hypochromic, microcytic anemia, which most often arises
secondary to iron deficiency.
The primary (and most dangerous if overlooked) mechanism of iron
deficiency is blood loss. Women of childbearing age are commonly iron
deficient because of menstruation. Adult males or postmenopausal
females, however, have no physiologic reason to be iron deficient and
therefore should be evaluated for occult blood loss in the gastrointestinal
tract. Malignancy within the gastrointestinal tract is typically ruled out
with an upper GI endoscopy and colonoscopy.
(Choice A) This patient's history of eating out and drinking a few beers
on the weekend are not suggestive of the severe malnutrition seen in
,alcoholics. The iron-to-calorie ratio of the normal W estern diet is 6 mg
iron for every 1000 calories. As a result, men and w omen w ho are not
menstruating, pregnant, or lactating usually have no dietary iron
shortage.
(Choice C) Hemolysis often presents with a normochromic, normocytic
anaemia. On peripheral blood smear, spherocytes or schistocytes tend
to be seen.
(Choice D) Hematologic malignancies such as leukaemia, lymphoma,
or multiple myeloma tend to be associated with normochromic,
normocytic anaemia. The decrease in erythropoiesis seen in these
patients results from hypersplenism or bone marrow mass replacement
by tumour.
(Choice E) The anaemia of chronic liver disease is usually normocytic
or slightly macrocytic with target cells on the peripheral blood smear.
(Choice F) Ingestion of the more commonly abused drugs is not
associated with microcytic anaemia.
2. A 42-year-old homeless male presents to the ER with blood-tinged
vomiting and abdominal discomfort. He admits drinking alcohol on a
regular basis and has been hospitalised several times in the past due to
alcohol intoxication. Physical examination is remarkable for a firm,
enlarged liver and shifting dullness to percussion. Examination of this
patient's peripheral blood smear reveals neutrophils with six to eight
nuclear lobes. The latter finding is best explained by:
, A. Blood lipid abnormality
B. Chronic blood loss
C. Folate deficiency
D. Myelodysplasia
E. Cobalamin deficiency
F. Hypothyroidism
Answer: C
Explanation:
Chronic alcoholism is associated with folic acid deficiency anaemia.
Folate deficiency in alcoholics results from poor dietary intake and
impaired folate absorption, utilisation and enterohepatic recycling. A
normal individual with a folate-deficient diet can maintain normal red
blood cell production for months due to folate recycling, while a
patient who consumes large amounts of alcohol will experience
anemia within a few weeks of beginning a folate-deficient diet. A
reduced form of folic acid, tetrahydrofolic acid, is necessary for the
synthesis of amino acids, thymidine and purines. Impaired
synthesis of nucleotides leads to defective DNA production in blood
cell precursors. This results in abnormal division of these cells and
leads to megaloblastic hyperplasia of the bone marrow. The
peripheral blood smear reveals pancytopenia and hypersegmented
neutrophils containing nuclei with greater than five nuclear lobes.
RBC abnormalities include ovalocytosis and macrocytosis (MCV
greater than 100 fl ).
(Choice A) Lipid abnormalities such as extreme hypertriglyceridemia
can cause acute pancreatitis. (Choice B) Chronic blood loss causes
iron deficiency anaemia.
, (Choice D) Myelodysplasia is a premalignant condition that
manifests with pancytopenia, impaired blood cell differentiation, and
clonal expansion of mutated hematopoietic cells in the bone
marrow. Elevated MCV can be present but hypersegmented
neutrophils are not seen .
(Choice E) Vitamin B 12 deficiency is not common in alcoholics.
Folic acid deficiency is more common.
(Choice F) Elevated MCV can be present in hypothyroidism but
hypersegmented neutrophils are not seen.
3. A 30-year-old female presents to the ER because of sudden-onset
abdominal pain and ascites. Complete blood count shows anaemia,
reticulocytosis, leukopenia, and thrombocytopenia. Imaging studies
show hepatic vein thrombosis. Flow cytometry of the hematopoietic cells
using monoclonal antibodies shows a deficiency of CD 55 and CD 59
proteins. Which of the following is the most likely cause of her anaemia?
A. complement activation
B. intracellular dehydration
C. splenic sequestration
D. factor V mutation
E. enzyme deficiency
F. mutation in beta globin chain
Answer: A
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