Management of two extremely aggressive signet ring cell colon carcinoma: a case series.

Signet ring cell carcinoma (SRCC) of the colon is a rare histologic subtype of colorectal cancer, accounting for <1% of cases, and is associated with aggressive clinical behavior and poor prognosis. We report two cases with advanced colonic SRCC. The first case involved a 58-year-old female with obstructing rectal SRCC and extensive pelvic invasion with adnexal metastasis. The second is a 45-year-old male with an obstructing splenic flexure SRCC and peritoneal dissemination, found to have microsatellite instability and multiple oncogenic alterations. Both cases required aggressive surgical intervention and illustrate the need for individualized, multimodal treatment strategies. Colonic SRCC is an uncommon but highly aggressive malignancy that frequently presents at an advanced stage. Early recognition, comprehensive pathologic and molecular evaluation, and coordinated multimodal management are critical to optimizing outcomes.