A 36-year-old man comes to the emergency department because of progressively worsening shortness of breath and fever for 2 days. He also has a nonproductive cough. He does not have chest pain or headache. His temperature is 38.1°C (100.6°F), pulse is 103/min, respirations are 26/min, and blood pressure is 130/70 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 91%. Pulmonary examination shows diffuse crackles. The spleen tip is palpated 4 cm below the left costal margin. The patient's serum fails to agglutinate horse erythrocytes. The agglutination test is repeated a week later and, again, no agglutination is noted. HIV testing is negative. Which of the following is the most likely cause of this patient's condition?

Question

A 36-year-old man comes to the emergency department because of progressively worsening shortness of breath and fever for 2 days. He also has a nonproductive cough. He does not have chest pain or headache. His temperature is 38.1°C (100.6°F), pulse is 103/min, respirations are 26/min, and blood pressure is 130/70 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 91%. Pulmonary examination shows diffuse crackles. The spleen tip is palpated 4 cm below the left costal margin. The patient's serum fails to agglutinate horse erythrocytes.  The agglutination test is repeated a week later and, again, no agglutination is noted.  HIV testing is negative.  Which of the following is the most likely cause of this patient's condition?

Quizplus · Accepted Answer

Eductional Objective: The Monospot test is positive in most cases of Epstein-Barr virus-associated mononucleosis.  In immunocompetent patients with a heterophile antibody-negative mononucleosis-like syndrome, the most likely diagnosis is cytomegalovirus infection.

A 36-Year-Old Man Comes to the Emergency Department Because of Progressively