Skin and underlying soft tissue containing a well-formed fistulous channel. The lining of the tract is dominantly composed of septic granulation tissue characterized by newly formed capillaries, stromal edema, and active fibroblastic proliferation. A dense inflammatory infiltrate is present, predominantly lymphoplasmacytic in composition, admixed with histiocytes and excess neutrophils. The surrounding tissue demonstrates variable degrees of fibrosis and reactive vascular changes. The adjacent squamous epithelium is partially denuded. No cytologic atypia, dysplasia, or invasive malignant process is identified in the examined sections.
Perianal fistula
Soft tissue fragments collectively measured 7x5.5x1.3 cm, the largest measuring 3x1.7x1.3 cm, totally embedded.
Perianal lesion, excision