ИСТИНА

OBJECTIVES: Exact endoscopic and morphological criteria of traditional serrated adenomas (TSAs) of the colon are still not indicated. We examined features of TSAs in patients of our population. METHODS: Of the 500 epithelial lesions, removed via colonoscope in 265 patients, 14/500 (2.8%) TSAs with different degrees of dysplasia and focus of adenocarcinoma in 1/14 (7.1%) were histologically identified. The key macro/micro features of TSAs and immunohistochemical studies with CD44, Ki67, Msi-1 and 1-and 3 - claudins antibodies were evaluated. RESULTS: Most of lesions were located in the left colon (9/14; 64.3%), being red in color (13/14; 92.9%), had size 0.5 - 4.5 cm. Macroscopically, 5/14 (35.7%) lesions were flat-elevated (0-IIa); 9/14 (64.3%) - protruding (0-Is, 0-Isp, 0-Ip). Three (21.4%) flat-elevated TSAs had pit-pattern II, difficult to differentiate from hyperplastic polyps (HP) and sessile serrated adenomas (SSA); 11/14 (78.6%) had pit-pattern IV, more typical for adenoma tubular-villous (ATV) and adenoma villous (AV). Immunohistochemically TSA is close to AT/ATV and fundamentally different from HP/ SSA, despite the fact that in current classification they belong to the group of serrated lesions. Statistically significant differences are: similar distribution of CD44 (surface) of the AT, ATV and TSA; similar levels of Msi-1 cytoplasmic response in AT, ATV and TSA; similar levels of Claudine-1 and -3 expression in ATV and TSA. CONCLUSIONS: Often TSA corresponds to red protruding type lesions with pit-pattern IV. The presence of characteristic ectopic crypts is almost impossible to distinguish from the branching of crypts in any ATV or AV, and there is no consensus on the number of ectopic crypts required for TSA verification. Given the low incidence of TSA, the similarity of endoscopic features and the absence of immunohistochemical differences between TSA and AT/ATV, the feasibility of TSA allocation in a separate classification group is debated and requires further study.