A Case of Anal Canal Adenoneuroendocrine Carcinoma with Pagetoid Spread

Abstract

Anal canal cancer with pagetoid spread (PS) is rare, and there have been very few reports of anal canal adenocarcinoma with neuroendocrine features with accompanying PS. The case of a 61-year-old man who presented with right leg edema, swelling of multiple lymph nodes, and perianal erythema is presented. Pathological examination of a biopsy from the lymph nodes suggested neuroendocrine carcinoma (NEC) in 70% and adenocarcinoma in 30%, with a Ki-67 labeling index greater than 80%. Perianal skin pathology was also NEC and adenocarcinoma with GCDFP-/CK20+/CK7+ immunohistochemical expression, indicating PS, but no anal canal tumor was confirmed by digital examination. Endoscopy showed a very small anal lesion, and these biopsies showed adenocarcinoma without obvious NEC. These pathological findings led to the diagnosis of anal canal adenoneuroendocrine carcinoma associated with PS. Computed tomography demonstrated paraaortic lymph node swelling and multiple lung metastases. After 3 courses of chemotherapy with a CPT-11+CDDP (IP) regimen, the lymph nodes and PS lesion shrank, and the right leg edema improved remarkably. Advanced anal canal adenoneuroendocrine carcinoma with PS was effectively treated with IP and controlled for a year.