Four Surgical Cases of Medullary Carcinoma of the Colon

Medullary carcinoma of the colon was formerly classified as poorly differentiated adenocarcinoma. The prognosis is relatively good, with a high degree of microsatellite instability and a predilection for the right colon.

The mean age of the 4 patients was 69 years (range, 47-90 years), with 2 males and 2 females. Preoperative biopsy results showed 3 cases of moderately differentiated adenocarcinoma and 1 case of poorly differentiated adenocarcinoma. All cases were right-sided colon cancer, with 3 cases of ascending colon cancer and 1 case of transverse colon cancer. One case was classified as cT3, 2 as cT4a, and 1 as cT4b. One case was cN-negative, and 3 were cN-positive. No cases were cM-positive. The approach was laparoscopic in 3 cases and robot-assisted surgery in 1 case. Postoperative complications included postoperative ileus in 1 case. Pathological staging was Stage II in 3 cases and Stage III in 1 case. All cases showed high microsatellite instability, and no adjuvant therapy was administered. All patients remain under observation, with no recurrences identified at the time of writing.

Medullary carcinoma is rare but has been increasing in recent years. This pathology shows characteristic histological features and immunophenotypes, and accurate diagnosis is important because of its effect on postoperative follow-up.