Abstract
Anal metastasis of colorectal cancer is very rare and is usually associated with a history of anal disease, including anal fistula, fissure, hemorrhoidectomy, and anastomotic injury. We report a case of rectal cancer with a synchronous anal metastasis consisting of adenocarcinoma of squamous cells without a history of anal disease. A 60-year-old woman had a chief complaint of melena. She had a 1.5-cm anal tumor on the perianal skin, and a Bollman type 2 rectal tumor on the Ra portion was found on colonoscopy. Biopsy of both tumors revealed a similar histology of well- to moderately differentiated adenocarcinoma. There was no sign of metastases in lymph nodes or other organs. For the purpose of diagnosis and treatment, transperineal local resection of the anal tumor was performed, and it was histologically identified as adenocarcinoma of squamous cells with no invasion to muscles, lymph ducts, or microvessels. The pathological margin was free. Then, to achieve radical cure, laparoscopic low anterior resection (LAR) with D3 lymphadenectomy was performed. The histological diagnosis of the anal tumor was adenocarcinoma of squamous cells without invasion to muscles, lymph ducts, or vessels. The surgical margin was completely free. Immunohistochemical analysis of both tumors revealed similar staining patterns, and the final diagnosis was rectal cancer with metastasis to the anal skin. The patient received no postoperative therapy, and no recurrences have been observed 12 months after surgery. We expect that our sphincter-preserving surgical strategy provided a good prognosis for the synchronous rectal cancer and anal metastasis. This is a rare report of a case with an anal metastasis of colorectal cancer on perianal squamous cells without a history of anal disease that was resected while preserving anal function.
Highlights
Many patients experience colorectal cancer metastasis, anal metastasis is very rare
We present a patient with synchronous rectal adenocarcinoma and anal metastasis on squamous cells in the absence of
The patient underwent laparoscopic lower anterior resection (LAR) and D3 lymphadenectomy to excise the rectal tumor. This tumor had the same pathology as the anal tumor, well- to moderately differentiated adenocarcinoma, and the cytokeratin (CK) 7 and CK20 immunohistochemical staining patterns were identical: CK7 was negative in both the rectal and anal the adenocarcinomas, while CK20 was positive in both tumors (Figs. 3 and 4)
Summary
Many patients experience colorectal cancer metastasis, anal metastasis is very rare. The anal tumor had a diameter of 1 cm and was irregularly shaped and slightly red on the outside of the dentate line (Fig. 2). Biopsy of both lesions revealed moderately differentiated carcinoma. The patient underwent laparoscopic lower anterior resection (LAR) and D3 lymphadenectomy to excise the rectal tumor. This tumor had the same pathology as the anal tumor, well- to moderately differentiated adenocarcinoma, and the cytokeratin (CK) 7 and CK20 immunohistochemical staining patterns were identical: CK7 was negative in both the rectal and anal the adenocarcinomas, while CK20 was positive in both tumors There is no sign of recurrence 12 months after surgery
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