P2333 - Synchronous Rectal Adenocarcinoma and Anal Squamous Cell Carcinoma in an Elderly Woman

Naszrin Arani, BSA¹, Robinder P. Abrol, DO², Diego C. Marines Copado, MD^3
1University of Texas Health Science Center at Houston, Houston, TX; ²University of Texas Medical Branch at Galveston, Galveston, TX; ³Houston Methodist Hospital, Houston, TX

Introduction: Synchronous colorectal cancer (sCRC) is defined as detection of more than one primary colorectal cancer simultaneously or within 6 months of initial diagnosis. It is a documented yet uncommon entity that has been described in 2.3% to 12.4% of colorectal cancer cases¹. Concurrent anal squamous cell carcinoma (SCC) in the setting of colorectal adenocarcinoma, however, is considerably rare and has only been described in a handful of cases. Here, we describe a case of a patient presenting with both a perianal and a rectal mass found to be anal SCC and rectal adenocarcinoma, respectively.

Case Description/Methods: A 75-year-old Caucasian female with a pertinent past medical history of diabetes, hypertension, hyperlipidemia, peptic ulcer disease, and asthma was initially admitted for symptomatic anemia. Initial hemoglobin was noted to be 7.8g/dL and iron studies were consistent with iron deficiency. The patient reported no family history of malignancy, and no history of tobacco, alcohol or NSAID use. A sizeable right-sided perianal mass was appreciated on physical examination. The mass was friable and mobile. Colonoscopy revealed a large rectal mass just proximal to the anal canal, which was biopsied and determined to be adenocarcinoma. Additionally, a few polyps were removed, including a tubulovillous adenoma, tubular adenoma, and a serrated adenoma—all from the rectum. Initially, the perianal mass was believed to be a possible extension of the rectal adenocarcinoma into the anal canal and along the external anal sphincter, and subsequent MRI supported the hypothesis. Pathological examination, however, confirmed that the perianal lesion was SCC.

Discussion: sCRC is defined in the literature as concurrent de novo colorectal cancers that did not arise by metastasis or local invasion. These are thought to arise in populations who have multiple risk factors for primary development of colorectal cancer including advanced age, male gender, and microsatellite instability. Much less is known about concurrent rectal adenocarcinoma and anal SCC as they arise from different cell lineages proximal and distal to the pectinate line, and to date there have been only a few cases described in the literature. Our case highlights the rarity of this unique clinical entity.




References:

1. Morton M, Melnitchouk N, Bleday R. Squamous cell carcinoma of the anal canal. Curr Probl Cancer. 2018 Sep;42(5):486-492. doi: 10.1016/j.currproblcancer.2018.11.001. Epub 2018 Nov 23. PMID: 30497849.

Disclosures:


Naszrin Arani, BSA¹, Robinder P. Abrol, DO², Diego C. Marines Copado, MD³. P2333 - Synchronous Rectal Adenocarcinoma and Anal Squamous Cell Carcinoma in an Elderly Woman, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.