Sections show fragments of fibroadipose tissue and focally ulcerated stratified squamous epithelium. The underlying dermis and subcutaneous soft tissues reveal disrupted, tract-like spaces devoid of a true epithelial lining. These tracts are lined by florid granulation tissue, organizing fibrin, and dense purulent exudate. Extending outward from these tracts into the surrounding stroma is a marked mixed inflammatory infiltrate composed of abundant neutrophils forming focal areas of suppuration and microabscesses, admixed with numerous lymphocytes, plasma cells, and histiocytes. The background stroma exhibits extensive dense collagenous fibrosis, marked neovascularization, vascular congestion, and focal hemorrhage, indicative of chronic recurrent tissue injury and ongoing repair. No granulomas, viral cytopathic effects, dysplasia, or evidence of malignancy are identified.
Recurrent high-type transsphincteric bilateral horseshoe fistula accompanied by an abscess.
Partially coverd soft tissue fragments collectively measured 6.5x4.5x1.5 cm, the largest measuring 3.8x2.2x1.5 cm.
Perianal tissue (fistula tract), excision: