Abstract
A 68-year-old woman diagnosed as having sigmoid colon cancer underwent sigmoidectomy (with D3 lymphadectomy) in February 2009. The pathological diagnosis was moderately differentiated tubular adenocarcinoma, ss, ly1, v1, n1, stage IIIa. Adjuvant chemotherapy with capecitabine was administered for 6 months after the surgery. She presented to our outpatient clinic in December 2009 (10months after sigmoidectomy) complaining of discomfort in the anal region. A protruding tumor measuring 2 cm was noted at the 3-o'clock position of the anus. Examination of biopsy specimens revealed moderately differentiated adenocarcinoma of the subepithelial layer, leading to a suspicion of metastasis of the sigmoid colon cancer. After obtaining informed consent, local excision was performed. The tumor was found to be a moderately differentiated adenocarcinoma with pathological features similar to those of the primary lesion ; therefore, anal metastasis was diagnosed. Because of concurrent hepatic and inguinal node metastases, she has been initiated on chemotherapy. We report an extremely rare case of metachronous anal metastasis after surgical treatment for sigmoid colon cancer. In this patient, the metastasis is highly likely to have occurred via arterial or lymphatic vessels.
