A Case of a Longstanding Perianal Lesion Presenting as Advanced Squamous Cell Carcinoma of the Anus

Squamous cell carcinoma of the anus (SCCA) is a rare malignancy with rising incidence. Early-stage disease has a favorable prognosis, but advanced tumors, nodal involvement, and p16-negative status worsen outcomes. We present a 63-year-old man with psychiatric comorbidities and long-term nicotine dependence who delayed care for a four-year ulcerated perianal lesion. Imaging revealed a large invasive anal mass and bilateral inguinal lymphadenopathy (T3N1a). Biopsy confirmed poorly differentiated, HPV-negative, p16-negative SCCA. He began chemoradiotherapy with supportive care. This case underscores the impact of delayed diagnosis and tumor biology on prognosis, highlighting the need for early recognition, multidisciplinary care, and smoking cessation.