A Case of Medullary Carcinoma of Colon Morphologically Resembling Non-Hodgkin's Lymphoma.

Medullary carcinoma of the colon is an unusual and unique histologic subtype of colorectal cancer. It is strongly associated with microsatellite instability, most commonly loss of MLH1 indicative of deficient mismatch repair proteins. Diagnosis is challenging as they do not display the usual histological pattern. Immunohistochemical staining also shows unusual findings like negativity for CD20 and CDX2. Here, we explore an intriguing case of medullary carcinoma of colon which showed loss of MSH2 and MSH6 and a morphology reminiscent of Non-Hodgkin's lymphoma.