Marjolin's ulcer arising in pilonidal disease: a case report and historical perspective.

We report a case of malignant transformation in a young woman with pilonidal disease-a rare manifestation of 'Marjolin's ulcer'. The patient initially presented to an outside hospital emergency department with an ulcer of the left buttock. Her family reported a longstanding mass present at this site prior to rupture. The patient had two ED visits and a surgical referral that did not result in biopsy, contributing to delayed diagnosis. She eventually presented to our wound clinic with a full-thickness, friable, frond-like ulcer with probable sacral extension. Immediate biopsy was performed and confirmed squamous cell carcinoma (SCC). Imaging revealed a buttock mass with lymphadenopathy. Fine-needle aspiration confirmed metastatic SCC in the inguinal lymph nodes. The disease was deemed unresectable and systemic therapy was begun. This case emphasizes the importance of biopsy in nonhealing ulcers, underscores the need for system-level processes to ensure follow-up, and demonstrates the enduring relevance of Marjolin's original 19th-century observations.