Abstract
Malakoplakia is a rare granulomatous disease of the genitourinary system. Gastrointestinal tract is the second most common site of involvement. It usually mimics a malignancy but its association with adenocarcinoma has been rarely reported. A 59-year-old male patient with the history of weight loss and rectal bleeding for two months prior to administration was referred to our hospital. Pre-operative CT scan revealed a large sigmoid colon mass with the extension and invasion to the serosal surface as well as multiple regional metastatic lymph nodes. The patient underwent sigmoidectomy with the primary pathologic diagnosis of adenocarcinoma. Pathologic examination revealed a moderately differentiated adenocarcinoma invading peri-colic adipose tissue and inflammatory reaction compatible with malakoplakia at the invasive borders of the tumor with the extension to the serosal surface. In the patients with gastrointestinal malakoplakia, the presence of possible adjacent malignancy should be screened. The possibility of over-staging should also be considered for adenocarcinoma cases in association with malakoplakia.