Abstract
A 62-year-old woman presented to our clinic because of anal pain was found having a palpable anal tumor by digital examination of the rectum. Colonoscopy revealed a ridging lesion with ulcer at the anal canal. A biopsy offered a diagnosis of neuroendocrine carcinoma. Apart from the anal canal tumor, an extramural tumor of the rectum and a presacral tumor were revealed on a CT scan. PET-CT scan showed abnormal uptakes of FDG in all the three tumors. Lymph node metastases of anal canal carcinoma were diagnosed, and abdominoperineal resection + D3 lymph node dissection was performed. The resected specimen included the anal canal tumor with the size of 25 × 25 mm in diameter. Histopathologically the tumor was substantially composed of proliferation of large oval-shaped cells with a large N/C ratio and the progression was rated as Stage IIIb. On immunohistochemistry, the anal canal tumor was strongly positive for synaptophysin and positive for chromogranin A, with the Ki-67 positive rate of 60%. Furthermore, we also confirmed well-differentiated adenocarcinoma and villous adenoma in the oral margin of the tumor. Neuroendocrine carcinoma arisen in the anal canal was thus diagnosed. We performed mFOLFOX (6) as adjuvant chemotherapy.
