PMC9886381_01
Photomicrographs of the colon. A - Signet ring cell carcinoma in colonic mucosa (H&Ex200); B - Immunohistochemical positive staining for CDX2 (X200); C - CK20 (X200); and D - Ki-67 (X200).
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The microscopic evaluation showed ulcerated mucosa with reactive epithelial changes and the lamina propria distended with signet ring cells exhibiting typical morphology of peripherally pushed eccentric nuclei and a large mucin vacuole (Figure 1A). Immunohistochemistry shows the tumor cells were positive for CDX-2 (Figure 1B), CK20 (Figure 1C), Cam 5.2, and focally for CK-7. Additionally, the neoplastic cells were strongly positive for p53, and the Ki67 index was 40% (Figure 1D).
Photomicrographs of the colon. Immunohistochemical reactions positive for: A - MSH6 (X200); B - PMS2 (X200); C - MLH1(X200); and D - MSH2 (X200).
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There was retained nuclear expression for all the Mismatch repair (MMR) proteins (Figure 2A to 2D).