Perianal Paget's Disease: A Challenge of Surgical Margins in Uncommon Clinical Presentations.

Perianal Paget's disease is a rare entity that often presents with scaly, erythematous plaques. It manifests with an insidious onset, a high frequency of concurrence with malignancy, and difficulties in ensuring clear resection margins. This case highlights the unexpected findings of perianal Paget's disease when completing an excision of invasive adenocarcinoma of the anus. Due to the difficulty with ambiguous borders, wide resection still had involved margins. The patient is currently completing topical treatments.