PMC10087263_01
The resected mass presented tubular adenoma with the anal squamous epithelium (A, x10; H&E). Highly atypical cell infiltrate by clusters in squamous epithelium (B, x200; H&E). Paget cells in squamous epithelium are large, with hyperchromatic and pleomorphic nuclei, pale or transparent cytoplasm, and obvious nucleoli (C, x400; H&E). Some Paget cells were more mucinous with eccentric nuclei and signet ring cell appearance (D, x400; H&E).
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Examination by H&E staining showed that the mass was a colorectal tubular adenoma with some perianal squamous epithelium (Figure 1).
Adenoma is composed of a large number of glands with high-grade intraepithelial neoplasia and lacks fibroproliferative matrix response (A, x20; H&E). The glands of high-grade intraepithelial neoplasia showing a more complex cribriform architecture and loss of polarity (B, x200; H&E). The cells of high-grade intraepithelial neoplasia showing nuclear enlargement and marked nuclear pleomorphism (C, x400; H&E). The neoplastic cells of the adenoma infiltrated the adjacent squamous epithelium (D, x400; H&E).
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The adjacent tubular adenoma showed the structure of high-grade intraepithelial neoplasia (Figure 2).
IHC showing intestinal phenotype of both the PPD and the adenoma: CDX2 (A, x100; IHC; Adenoma in the upper left part and PPD in the lower right part), CDX2 (B, x400; IHC; The left half is adenoma and the right half is PPD), CK20 (C, x100; IHC; Adenoma in the upper left part and PPD in the lower right part), and CK20 (D, x400; IHC; the left half is adenoma and the right half is PPD). IHC, immunohistochemistry; PPD, Perianal skin Paget disease
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Immunohistochemistry showed that the atypical cells and adjacent adenomas showing an intestinal phenotype were positive for CDX2, CK20, and MUC2 (Figure 3).