(BMJ)—A man in his 50s with a 5-year hx of constipation had a nontender rectal lesion found on digital rectal exam. He had no rectal pain and had been self-administering enemas once weekly for the past 3 years, without relief of constipation. Colonoscopy demonstrated the lesion as shown. Bx was negative for neoplasm. What’s the dx?
Syphilitic chancre
HSV infection
Solitary rectal ulcer syndrome
Medication-related ulcer
Lymphogranuloma venereum
You are correct. Treponema pallidum particle agglutination assay and toluidine red unheated serologic test (TRUST) titers were positive, confirming syphilitic chancre. Chancres are usually genital but may also be found in the anal, rectal, or oral regions or on the hands. Chancre of the rectum is often asymptomatic but may cause mild rectal pain or discomfort, constipation, rectal bleeding, and, occasionally, rectal secretions. MRI, bx, medication hx, and bloodwork ruled out other possible causes.

The patient was PCN intolerant, so he was treated with IV ceftriaxone 2 g daily x2wk. His titer increased to 1:8, suggesting a poor response to the initial tx, and there was no improvement in MRI findings; rectal wall thickening was still present, and the lymph nodes had become necrotic. He ultimately responded to PO doxycycline x30 days. The lesion resolved, but his constipation persisted and was believed to be unrelated to the syphilis dx.

BMJ 2021;372:n316