Anal adenocarcinoma with perianal Paget's disease: A case report.

Background: Anal canal adenocarcinoma with secondary perianal Paget's disease (PPD) is clinically rare and exhibits atypical symptoms, often misdiagnosed as benign conditions such as hemorrhoids or perianal eczema, leading to delayed treatment. Further summarization of diagnostic and therapeutic key points, as well as reasons for misdiagnosis, is necessary to enhance clinical awareness.

Case summary: A retrospective analysis was conducted on a 72-year-old female patient with a 2-year history of perianal moisture, pruritus, and hematochezia, who was repeatedly misdiagnosed with mixed hemorrhoids. The diagnosis of anal canal adenocarcinoma with secondary PPD was confirmed through colonoscopy, perianal skin biopsy, and immunohistochemical staining (CK7, CK20, etc.). The patient underwent 3D laparoscopic-assisted abdominoperineal resection (APR) with extended perianal skin excision, achieving negative margins and primary wound healing. No recurrence or metastasis was observed during the 12-month follow-up.

Conclusion: Secondary PPD has a high misdiagnosis rate. Clinicians should maintain a high index of suspicion for elderly patients with prolonged perianal symptoms (e.g., pruritus, hematochezia > 6 months) and promptly perform colonoscopy and immunohistochemical testing for definitive diagnosis. APR combined with extended perianal resection is an effective treatment, and standardized long-term follow-up is crucial for prognosis.