PMC6092986_01
Endoscopic photographs showing normal colonic mucosa (top left), abnormal polypoid mass (top right and bottom left), and sessile polyp (bottom right).
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fig1
Findings were significant for 9-10 sessile polyps in transverse, descending, and sigmoid colon with large cluster of irregular appearing polyps in the sigmoid (Figure 1).
Immunohistochemical studies for PMS2 deficient adenocarcinoma, 40X. (a) H&E: moderately differentiated adenocarcinoma with crowded glands and minimal stroma. (b) CK7: focal positive immunostaining for CK7. (c) CK20: negative immunostaining for CK20. (d) Villin: focal minimal superficial (brush border) immunostaining for villin. CDX2 was also focally positive (not shown). (e) MLH1: intact nuclear immunostaining for MLH1 (no loss of expression). (f) MSH2: intact nuclear immunostaining for MSH2 (no loss of expression). (g) MSH6: intact nuclear immunostaining for MSH6 (no loss of expression). (h) PMS2: loss of nuclear immunostaining for PMS2 in both tumoral cells and background lymphocytes. Positive tissue control stains were appropriately positive (inset).
CRIG2018-8657823.002.jpg
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fig2
Immunohistochemical staining demonstrated the carcinoma to be positive for CDX-2, villin, and CK7 and negative for CK20 and WT-1 (Figure 2). There was again loss of expression of PMS2 in both tumor and nontumoral cells (Figure 2) consistent with complete protein loss.