Partially ulcerated anal mucosal fragments by related invasive nests and cords of malignant squamous epithelial cells extending beyond the basement membrane with associated with a desmoplastic stromal response and chronic inflammatory infiltrate. The tumor demonstrates moderate squamous differentiation, characterized by polygonal cells with eosinophilic cytoplasm, distinct intercellular bridges, and focal keratinization, including small keratin pearls. Tumor nuclei are enlarged and pleomorphic with irregular nuclear contours, vesicular chromatin, and occasional prominent nucleoli. Mitosis is active.
The adjacent surface epithelium shows full-thickness squamous atypia with loss of maturation and increased mitotic activity, without stromal invasion, consistent with squamous carcinoma in situ (high-grade squamous intraepithelial lesion).
Lymphovascular invasion is noted. Depth of invasion, tumor size, and margin status cannot be assessed due to the fragmented nature of the biopsy.
Anorectal mass.
Soft tissue fragments collectively measured 1.2 cm, totally embedded.
Anorectal mass, endoscopic biopsy: