A 27-year-old man with HIV comes to the clinic with symptoms of pain every time he swallows (odynophagia) He is not on any antiretroviral therapy and otherwise feels well. Examination of the mouth and pharynx are normal. Which of the following is the most likely diagnosis?

Painful swallowing can be caused by Candida or herpes infection of the esophagus, or pill-induced esophagitis. Patients with immunodeficiency states (eg, AIDS) may have herpetic, candidal, or CMV esophagitis, as well as tumors (lymphoma, Kaposi sarcoma). Candida infection is more common than the other etiologies listed, and therefore the most likely diagnosis.