Medullary carcinoma of the colon: a case series and review of the literature.

BACKGROUND Most colon cancers are adenocarcinoma of the colon, which present with a typical histological type. However, a relatively newly-recognized subtype, called medullary carcinoma of the colon, has been characterized. This type is generally divided into subtypes of poorly-differentiated and undifferentiated medullary carcinoma. Only a handful of studies have been conducted thus far, mostly focusing on immunohistochemical and clinical characteristics of the disease. PATIENTS AND METHODS Herein we present two cases seen at our hospital within one academic year. The first is the case of a 79-year-old African-American woman, who presented with generalized weakness and gait unsteadiness ultimately diagnosed with a Stage IIIB medullary carcinoma of the proximal colon at the time of surgery, but later found to have metastases to a single paraesophageal lymph node. The second is a case of a 79-year-old Caucasian woman, who presented with several weeks of malaise, nausea, and diarrhea leading to diagnosis of a stage IIB medullary colon carcinoma now receiving chemotherapy. CONCLUSION Although these tumors tend to be right-sided and therefore present at an advanced stage, distant metastasis is rare at presentation and is primarily to the liver or regional lymph nodes. Only one study has been performed regarding short-term outcomes, which failed to reach statistical significance, but trended towards better prognosis compared to poorly-differentiated and undifferentiated colonic adenocarcinomas.