Mucous Membrane Ulcers in an Immunocompromised Patient—Quiz Case

A 62-year-old man presented with a 10-day history of painful ulcerated lesions on his tongue and penis. His medical history was remarkable for a low-risk myelodysplastic syndrome, which had been treated with antithymocyte globulin and cyclosporine 1 month earlier. Clinical examination showed a large, deep, and exquisitely tender ulceration on the glans penis, with a purulent exudate (Figure 1). Also, 3 linear superficial erosions were detected on the dorsum of the tongue (Figure 2). Exudate cultures yielded Escherichia coli and Enterococcus faecalis. Antibiotic therapy with ciprofloxacin and metronidazole was unable to improve the clinical lesions, which enlarged after a few days. Laboratory evaluation was significant for a severe lymphocytopenia (lymphocytes, 300/μL [to convert to 10/L, multiply by 0.001]). No other cutaneous or extracutaneous signs or symptoms of visceral involvement were detected. Serologic tests were negative for human immunodeficiency virus (HIV). Skin biopsy findings are shown in Figure 3. What is your diagnosis?