Question 1
A Patient with a 30-year history of type 2 diabetes mellitus presents with evidence of
reduced cardiac output. She has slight arterial hypotension. Rales are heard bilaterally at
the lung bases. Pulmonary capillary wedge pressure is significantly elevated, but
echocardiography indicates reduced early filling and reduced end-diastolic left ventricular
volume with preserved ejection fraction. There is no sign of mitral valve malfunction. What
is the most likely cause of the reduced cardiac output?
A. Decreased left ventricular end-diastolic pressure
B. Excessive afterload
C. Excessive left ventricular preload
D. Failure of left ventricular contractility
E. Reduced left ventricular compliance
The correct answer is E. The evidence indicates that pressure in the pulmonary circuit is
elevated with no sign of obstruction of flow through the left atrium into the ventricle.
Despite the high input pressure, there is reduced ventricular filling and end-diastolic filling:
preload is low. Reduced end-diastolic volume at high filling pressure reflects pathologically
reduced ventricular compliance.
Questions 2
Approximately how many tertiary bronchi are there in a pair of lungs?
A. 10
B. 20
C. 30
D. 40
E. 50
The correct answer is B. There are 10 tertiary bronchi in the right lung and 8 to 10 in the
left lung. This results in approximately 20 in both lungs.
Question 3
A patient who has a hacking cough suspected of being due to bronchopneumonia is asked to
produce a sputum sample from deep in the respiratory tract. The laboratory makes a Gram
stain of the material to study it for bacteria. The presence of which of the following cell
types on the slide would help confirm that the sample really was from deep in the
respiratory tract, rather than simply being saliva?
A. Ciliated columnar cells
B. Eosinophils
C. Neutrophils
D. Simple squamous cells
E. Stratified squamous cells
The correct answer is A. A frequent real-life clinical problem is that the "sputum" sample
people make may just be "spit." Laboratory people learn to look for isolated respiratory
epithelial cells (that form the pseudostratified ciliated respiratory epithelium lining the
trachea and parts of the bronchi) in their slides because the presence of these cells
substantiates that a sample was from a deep cough specimen. (The cells could also be from
sinus mucus that drains down the back of the throat because respiratory epithelium can also
occur in the nose and sinuses. Even if this is true, the pathogens causing the sinusitis are
likely to be similar to those causing the pneumonia.)
Question 4 –
A laboratory specimen is fixed, embedded in paraffin, sectioned with a microtome, and then
stained with hematoxylin and eosin. Microscopic examination of the tissue would most likely
reveal which of the following?
A. Blue areas of calcification
B. Blue colloid in the thyroid gland
C. Blue erythrocytes
D. Pink bacteria
E. Pink nuclei
The correct answer is A. Calcified areas appear bluish-purple with hematoxylin and eosin
stain. Colloid and red cells would appear pink to red; bacteria and nuclei would appear blue.
Questions 5 –
A 41-year-old homeless man is admitted to the hospital from the emergency department
with fever, night sweats, cough, and weight loss. A chest x-ray shows upper lobe infiltrates
and a 1-cm cavity in the left upper lobe. Sputum is obtained from the individual and sent to
the laboratory for staining and culture. Which of the following staining procedures would be
most appropriate for the specimen?
A. Congo red
B. Periodic acid-Schiff
C. Prostate-specific antigen immunofluorescence
D. Trichrome stain
E. Ziehl-Neelsen stain
The correct answer is E. The man in question most likely has tuberculosis. An acid-fast
staining method, such as the Ziehl-Neelsen or Fite stain, may reveal acid-fast bacilli
(Mycobacterium tuberculosis) in the sputum sample.
Question 6 –
A renal pathologist shows a medical student a slide of kidney that has large, pink, acellular
deposits in the glomeruli. The pathologist then adjusts his microscope so that the slide is
illuminated with polarized light, and the glomerular deposits now look bright green. Which of
the following stains did he use?
A. Congo red
B. Gram stain
C. Periodic acid-Schiff
D. Reticulin
E. Trichrome
The correct answer is A. The description of pink amorphous deposits that look green
under polarized light is classic for amyloidosis stained with Congo red.
Question 7 –
A biopsy of lung tissue shows extensive fibrin deposition in the alveoli. On a hematoxylin
and eosin-stained slide, the fibrin would most likely be which of the following colors?
A. Blue
B. Green
C. Red
D. White
E. Yellow
The correct answer is C. Hematoxylin and eosin stain is the most common stain used in
histology, and you should be familiar with its staining qualities, which are summarized in
Table 1. Hematoxylin stains many things blue to purple, and eosin stains others, including
fibrin, pink to red.
Question 8 –
A patient has a poorly differentiated tumor. The laboratory reports that the tumor is positive
for cytokeratin. This finding was most likely determined with which of the following
methodologies?
A. Histochemistry
B. Immunofluorescence
C. Immunohistochemistry
D. Protein electrophoresis
E. Transmission electron microscopy
The correct answer is C. It is worth getting a feel for how the various laboratory tests you
will see are actually performed. Some stains are histochemical, which are mostly easy to do
(and are inexpensive and widely available) because they just involve dipping slides in a
series of reagents. The histochemical stains highlight general features of slides, such as
mucin production, iron deposition, or collagen deposition. Other stains are
immunohistochemical (such as cytokeratin), which use antibodies directed against cell
proteins, are difficult to perform consistently (and hence tend to be available only in big
laboratories), are expensive, and are mostly used to define the exact types of unusual
tumors.