[9] CLINICO-HISTOPATHOLOGICAL FEATURES OF COLONIC ADENOCARCINOMA IN YOUNG (<50YEARS) PATIENTS WITH SPECIAL REFERENCE TO MICROSATELLITE INSTABILITY STATUS

Micro satellite instability Aims. To study the clinic-histopathological features and Microsatellite instability (MSI) status of colorectal carcinoma (CRC) in patients < 50 years of age. Methods. Sixty-one cases of CRC were studied in detail. Complete history, clinical details, colonoscopic findings and gross and microscopic features were noted. Histological type, grade of tumour and histological features like tumour infiltrating lymphocyte (TIL), Crohn like lymphoid aggregates and peritumoral lymphocytes were noted. Immunohistochemistry for MSH‐2 and MLH‐1 was done in 30 cases of <50 years of age. Results. Proximal location, mucinous and signet ring cell carcinoma were more common in young (<50 years of age) as compared to elders (<50 years of age) (47.3%, 19.5 % and 16.7 % vs. 17.4%, 8 % and 12%). Mucinous evidence (52.7%); TIL (94.4%) and Crohn‐like lymphoid aggregates (52.7%) were also common in younger patients. Nineteen were labeled as MSI +ve, of which 13 cases were MSI‐H and 6 MSI‐L. Out of 19 MSI +ve cases, 2 had +ve family history, 17 cases were labeled as sporadic. MSI +ve cases were proximally located (63.2%), had mucinous (31.5%) and signet ring cell morphology (42.0%), TIL (89.5%) and Crohn‐like lymphoid aggregates (73.5%). Conclusion. Sporadic cases with MSI in young show unique clinicopathologic spectrum. Studies for denovo /somatic germ line mutation may help in further elaboration