Less common rectal tumors

Abstract

While the majority of malignant rectal neoplasms are adenocarcinomas, and the majority of anal malignancies are squamous cell carcinomas, other less frequent histologic subtypes are encountered in the rectum and anus. They include carcinoid tumors, rectal lymphoma, anorectal melanoma, neuroendocrine carcinoma (NEC) of the rectum, vascular lesions, squamous cell carcinoma of the rectum and its variants, rectal sarcomatous lesions, including gastrointestinal stromal tumor (GIST) of the rectum, leiomyosarcoma and Kaposi’s sarcoma. These less common histiotypes will undoubtedly be encountered in clinical practice and deserve mention. Due to their rarity, these tumors frequently pose a challenge with diagnosis, staging, pathology, management, and follow-up. In this chapter we will discuss tumor biology, natural history and treatment options for these rare tumors and offer a data-driven, evidence-based approach to guide their management.