case_images: PMC10750828_01
case_images: Photomicrograph of the polypoid lesion showing in A and B - unremarkable anal mucosa with underlying tumor disposed in sheets of epithelioid and balloon cells having abundant eosinophilic to vacuolated cytoplasm with central to eccentric hyperchromatic nucleoli; C - shows overlying rectal mucosa with subepithelial zone infiltrated by tumor. (H&E, A - 100X, B - 200X, C - 100x)
case_images: autopsy-13-e2023459-g01.jpg
case_images: PMC10750828_01_autopsy-13-e2023459-g01.jpg
case_images: gf01
case_images: The histological examination revealed the anorectal mucosa with an underlying tumor disposed in sheets and islands of foam cells with interspersed focally pigmented epithelioid to spindle cells with prominent nucleoli (Figure 1A). The foam (balloon) cells were large with abundant vacuolated cytoplasm, central to eccentric hyperchromatic nuclei, and inconspicuous nucleoli (Figure 1B).
case_images: Immunohistochemical findings: A - Tumor showing diffuse expression for S-100, B - HMB-45, C - Melan A, negative expression for D - Ki 67 proliferation index. (Original magnification, A-D DAB 200x)
case_images: autopsy-13-e2023459-g02.jpg
case_images: PMC10750828_01_autopsy-13-e2023459-g02.jpg
case_images: gf02
case_images: S-100 protein (Figure 2A), HMB-45 (Figure 2B), Melan-A (Figure 2C), and negative expression for pan-cytokeratin and epithelial membrane antigen (EMA). Staining with Ki-67 was positive in almost 40-50% of the tumor cells (Figure 2D).