[SERRATED COLORECTAL ADENOCARCINOMA].

The aim: To present a clinical case of serrated colon adenocarcinoma. To demonstrate morphological and genetic features of these tumors and to determine their clinical management.

Key points: Described case shows diagnostics of serrated colon adenocarcinoma. A 67-year-old woman presented for colonoscopy because of long constipation besides abdominal pain and distention have appeared recently. Colonoscopy was performed and she was found to have a 3.0 x 3.0-cm tumor next to hepatic flexure and pedunculated 1.2x0.7 cm polyp in sigmoid colon (type lp according to Paris classification). Endoscopic biopsies of these lesions were consistent with serrated adenocarcinoma and tubulovillous adenoma with foci of severe dysplasia. Additional diagnostic methods revealed no distant metastases. Patient was under went right hemicolectomy with D3 lymphodissection, lesion in sigmoid colon was removed using snare with electrocautery. Final pathology revealed no residual tissue in margins and no malignant cells in removed lymph nodes. Genetic diagnostics by PCR found high level of microsatellite instability and positive CpG island methylator phenotype (CIMP+) in tumor tissue.

Conclusions: According to WHO classification serrated lesion are considered to have malignant potential. They serve as the precursors for approximately 10% to 15% of sporadic colorectal cancer developed through the serrated pathway. These tumors were named serrated adenocarcinoma and had special morphological criteria that allow us to differentiate them with colorectal adenocarcinomas developed through the traditional pathway. Serrated adenocarcinoma has high level of microsatellite instability and positive CpG island methylator phenotype (CIMP+). Presence of microsatellite instability in tumor determines its more favorable prognosis because of tumor immunogenicity. Besides this type of cancer is more often responding to therapy with fluoropyrimidines.