USMLE posts monthly Step 2 stumper question
This month, the question relates to pain and weight loss:
A 43-year-old woman with HIV comes to the physician because of painful swallowing, substernal chest pain and weight loss for one month. She takes no medications. Her temperature is 37.8 °C (100 °F). Her CD4+ T-lymphocyte count is 41/mm3. Upper endoscopy shows inflammation and a large, deep ulceration of the distal esophagus. A biopsy specimen of the esophagus shows inflammation and small blood vessel endothelial cells with markedly enlarged, smudgy, eosinophilic nuclei. Which of the following is the most likely cause of this patient's symptoms?
A. Acid reflux B. Candida C. Cytomegalovirus D. Herpes simplex E. Herpes zoster
The answer is Cytomegalovirus; patients with HIV/AIDS often get infectious esophagitis and the causative agents can be found by performing an endoscopy with biopsy which usually leads to one of three answers -- Candida, herpes simplex or cytomegalovirus. However, this patient had odynophagia, painful swallowing, which should empirically rule out Candida. Review of the biopsy specimen to determine the cause between herpes simplex and cytomegalovirus identifies the presence of small numbers of cells with noticeably large nuclei showing intranuclear viral inclusions. Another hint that it is cytomegalovirus is the patient’s CD4+ T-lymphocyte count is below 50/mm3.
Acid reflux (A) would only produce inflammation, it would not show ulceration of the esophagus. Candida (B) would cause large white plaques which, when examined under a microscope would show hyphal and yeast forms. Herpes simplex (D) would only be diagnosed after multinucleated cells with nuclear viral inclusions was found. Herpes zoster infection (E) rarely involves the esophagus.
The most important tip to remember in this question is the patient’s CD4+T-lymphocyte count was below 50/mm3, which almost always leads to cytomegalovirus in patients with HIV/AIDS.
For more prep questions on USMLE Steps 1 and 2, visit https://wire.ama-assn.org/education/usmle-prep.