Kolorektal medüller karsinom tanisina histopatolojik yaklaşim ve klinikopatolojik önemi

Background and Aims: Medullary carcinomas are rare tumors, constituting less than 1% of all colorectal cancers, characterized with nongland-forming, solid sheets of malignant cells with vesicular nuclei, prominent nucleoli and abundant pink cytoplasm. They are important tumors due to their relationship with high microsatellite instability and Lynch syndrome. We reviewed the clinicopathological features of medullary carcinomas. Materials and Methods:The resection specimens of 50 poorly differentiated adenocarcinomas, examined between 2002-2011 and showing at least focal areas with a solid growth pattern, were retrospectively reviewed, re-classified, and re-staged according to the World Health Organization 2010 classification for features of medullary carcinoma. The clinicopathological findings were compared statistically with poorly differentiated adenocarcinomas using nonparametric tests.Results: Seven cases were reclassified as medullary carcinoma, constituting 0.62% of 1128 colorectal tumors diagnosed using their resection specimens within the given period. Three of the cases were female, and the mean age was 62± 5.9 years (range: 41-80 years). Tumors were located in right colon (5/7), showed expansive growth pattern (6/7), prominent Crohnas-like lymphoid reaction (5/7), and tumor-infiltrating lymphocytes (7/7). When compared with 43 poorly differentiated adenocarcinoma cases, the lower incidence of lymphovascular invasion (28% versus 39.5%), pT4 (14.3% versus 20.9%) and pN2 tumors (14.3% versus 30.2%) and absence of perineural invasion, tumor qbuddingq and qdirty necrosisq (p=0.002, chisquare) were noteworthy. Conclusions:Medullary carcinomas are rare tumors located predominantly in the right colon, showing an expansive growth pattern, and respectively, lower tumor and lymph node stages. They deserve special attention due to their special histological features and differential diagnostic pitfalls. The clinicopathological findings in our series are consistent with the previous literature. This study is presented to draw attention to this rare but important entity, which may have significant clinical implications in view of its relationship with Lynch syndrome.