A Case of Neuroendocrine Carcinoma of the Anal Canal Adjacent to Signet Ring Cell Carcinoma of the Rectum

Abstract

Neuroendocrine carcinoma is a disease carrying an extremely poor prognosis. We have recently experienced a case of neuroendocrine carcinoma of the anal canal adjacent to signet ring cell carcinoma of the rectum. The case involved a 73-year-old man who presented with bleeding at defecation and anal pain. Colonoscopy revealed a concave lesion in the rectum Rb and a tumor in the anal canal. A CT scan showed lymph node metastasis at the left inguinal region. We thus made the diagnosis of anal canal carcinoma with left inguinal lymph node metastasis, and performed abdominoperineal resection, bilateral lateral lymph node dissection, and left inguinal lymph node dissection. Histopathological findings of the rectal carcinoma showed signet ring cells which had invaded full thickness of the wall and the adventitia ; those of the anal canal carcinoma showed solid acinous hyperplasia of atypical cells which had invaded up to the adventitia. Immunohistochemistry resulted in Synaptophysin and Chromogranin positive. Consequently, we made the diagnosis of neuroendocrine carcinoma. The rectal and the anal canal carcinomas were adjacent to each other, and the almost all dissected lymph nodes involved metastases of rectal signet ring cell carcinoma. The patient developed recurrence in an early time after the operation and underwent chemotherapy, however, he died of the present disease 2 years and 2 months after the operation.