A 67-year-old Chinese Man presented with a 1-month history of tender perianal ulceration. He had no lesions elsewhere and was constitutionally well. His medical history was significant for diabetes mellitus and hypertension. He was married to his 1 lifetime sexual partner and had no history of anal intercourse, perianal trauma, or sexually transmitted infections.
Physical examination revealed ragged, irregular perianal ulcers bilaterally with purulent discharge and surrounding erythema and induration over the gluteal region (Figure 1). Findings from rapid plasma reagent assay, herpes simplex viral isolation, and human immunodeficiency virus serologic testing were all negative. A skin biopsy was performed, and the specimen was stained with hematoxylin-eosin (Figure 2) and Ziehl-Neelsen stains (Figure 3).