A Case of Serrated Polyposis Syndrome Resulting in Metachronous Medullary Carcinoma of the Transverse Colon

Abstract

The patient was a 69-year-old woman who had multiple hyperplastic polyps in the whole colon for more than 10 years and had undergone surgery for transverse colon cancer during this period. She had been aware of bloody stool for 3 years after interruption of the postoperative periodic checkups, and was diagnosed as having medullary carcinoma of the transverse colon. Laparoscopic resection of the transverse colon was performed, and the patient was discharged from the hospital on the 11th postoperative day.

Medullary carcinoma of the colon is a relatively newly classified histological type, and it was once defined as poorly differentiated carcinoma. In 1997, a medullary type was reported in a case of a large tumor with peritumoral lymphocytic infiltration and MSI-high. It was later described as medullary carcinoma in the third edition of the WHO classification in 2000. Medullary carcinoma is a tumor with a relatively good prognosis and is most commonly seen in the right colon. Serrated polyposis syndrome is also a relatively new concept, and carcinogenesis from sessile serrated adenoma/polyps (SSA/P) is attracting attention. A case of advanced medullary carcinoma of the transverse colon, which was diagnosed 3 years after the 4-year checkup for primary colon cancer is reported.