Small cell neuroendocrine carcinoma disguised as an external hemorrhoid.

This article describes a patient who presented to the ED with persistent nausea and vomiting, constipation, weight loss, and a new complaint of an external hemorrhoid and hematochezia with stooling. Comprehensive diagnostic evaluation included imaging studies that showed extensive metastatic disease but did not identify a primary neoplasm. Biopsy of the external hemorrhoid revealed small cell neuroendocrine carcinoma of the anal canal.