Question 206
A 64-year-old male is involved in a motor vehicle accident and sustains lethal injuries. The forensic pathologist performing the autopsy examines the organs histologically. In the microscopic section of the lung, she identifies the lesion pictured in the image. Of the following, what was the most likely etiology for this change?
A. Trauma
B. Long standing hypertension
C. Previous exposure to chlorine gas
D. Infection with Strongyloides stercoralis
E. Use of cigarettes
Answer for Question 206
Answer: E (Use of cigarettes)
Explanation: The lesion is squamous metaplasia (with some probable dysplasia, as the nuclei are large and there is a mitotic figure at the black arrow). Squamous metaplasia in the lung is most commonly due to cigarette smoke. The chemicals in the smoke irritate the respiratory mucosa, and metaplasia occurs (i.e., change to a type of epithelium that can better handle the irritant). Metaplasia can lead to dysplasia and dysplasia leads to neoplasia. Previous infection with chlorine gas and infection with Strongyloides stercoralis could potentially lead to squamous metaplasia, but, their incidence would be much more rare than cigarette smoking–remember, on the USMLE, more than one answer may be possible–but, only one answer is the best–don’t be fooled by the distractors.
Question 207
A 43-year-old male with a history of hypertension, diabetes mellitus, and a hereditary clotting disorder presents to the emergency room accompanied by his wife and complaining of sudden onset of severe abdominal pain. Physical examination reveals a blood pressure of 151/93 mmHg, pulse rate of 106 bpm, and pain to palpation in the right upper quadrant of the abdomen. The disease process causing his symptoms is illustrated below. Of the following, what was the most likely mechanism by which it occurred?
A. Decreased flow through an artery
B. Decreased flow through a vein
C. Decreased flow through an artery and a vein
D. Decreased flow through two veins
E. Decreased flow through two arteries
Answer for Question 207
Answer: C (Decreased flow through an artery and a vein).
Explanation: The image is an infarct of the liver (the coagulative necrosis is at the blue star and the viable hepatocytes are at the yellow star). In the liver, red infarcts generally occur because of a dual blood supply (the black arrow indicates extravasated red blood cells, which could make the infarct appear more red grossly). The dual blood supply to the liver is arterial (hepatic artery) and venous (portal vein). This patient could have atherosclerosis of the hepatic artery and developed a thrombus in the portal vein. Neither vessel needs to be completely obstructed, just compromised.
Question 208
A dermatopathologist is reviewing a punch biopsy of a skin lesion taken by a referring clinician. In the dermis, the pathologist identifies the pigment illustrated in the image below. Of the following, what is the most likely diagnosis?
A. Invasive melanoma
B. Past tattoo procedure
C. Benign soft tissue tumor
D. Resolving bruise
E. Parasitic infection
Answer for Question 208
Answer D (Resolving bruise)
Explanation: The pigment pictured is hemosiderin (it can be described as chunky (i.e., variable in size–yellow arrows are good examples of the variability in size and shape) and yellow-brown in appearance). Hemosiderin is deposited when red blood cells break down, such as after a bruise. Melanin is more finely stippled and black, as would be tattoo pigment.
Question 209
A 53-year-old male with a history of hypertension and diabetes mellitus type II collapses while mowing the lawn. Despite resuscitative measures, he is pronounced dead. To determine the cause of death, the medical examiner performs an autopsy and identifies the finding in the image below (reference: the normal interventricular septal thickness is 1.5 cm or less). Of the following, which type of protein is most increased in amount in this organ?
A. Fibrillin
B. Endothelin
C. Pepsin
D. Actin
E. Cytokeratin
Of the following, what process has occurred in this organ?
A. Metaplasia
B. Dysplasia
C. Hyperplasia
D. Hypertrophy
E. Atrophy
Answer for Question 209
Answers: D (Actin) and D (Hypertrophy)
Explanation: The thickness of the wall is increased. The yellow line on the interventricular septum indicates the normal maximal thickness of a heart wall (i.e., 1.5 cm); the white line indicates the thickness of this heart’s interventricular septum. Due to the patient’s hypertension, the heart has undergone hypertrophy (as cardiac myocytes are essentially not capable of division, hyperplasia of the muscle would not occur); the most common protein in the cell is actin, and as hypertrophy of the cells would require an increase in the amount of contractile protein, the best answer is actin. Fibrillin is found in the aorta and other blood vessels, but not significantly in the myocardium and cytokeratin is a marker for epithelial cells (such as squamous and glandular cells).
Question 210
A pathology resident is conducting an autopsy during his first month of residency. While palpating the lungs of a 53-year-old male who had a 45 pack-year smoking history and died from metastatic squamous cell carcinoma of the lung, the resident identifies the lesion illustrated in the image below. Of the following, what process has occurred?
A. Hypertrophy
B. Hyperplasia
C. Metaplasia
D. Atrophy
E. Neoplasia
Answer for Question 210
Answer: C (Metaplasia)
Explanation: The lesion is normal bone, but it is in the lung, which would represent a form of osseous metaplasia. Although much of the right side and bottom of the image exhibit the change, the yellow areas are representative areas of the osseous metaplasia. Layering of the bone can be identified and osteocyte lacunae (i.e., the small open spaces) are visible.
