2117 Anal Squamous Cell Carcinoma Presenting as a Rectal Mass

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INTRODUCTION: Anal squamous cell carcinoma (SCC)typically presents as an anal mass. It rarely presentsin the rectumalone. Limited literature exists to discuss regarding optimal management for this unique presentation. We present a patient withanal SCC manifesting as a rectal mass and reviewher management. CASE DESCRIPTION/METHODS: A 73 year-old woman with esophageal reflux presented to our office with chronicrectal bleedingand constipation.She denied anal pain. Colonoscopy revealed a 1.2 cm massin the anterior rectum, 2 cm from the anal verge (Figure 1). Biopsies revealed focally invasive nonkeratinizing SCC (Figure 2). On rectal endoscopic ultrasound (EUS), the mass was confined to the anus andextended from the anorectal canal into the rectum (Figure 3). Submucosal invasion was noted, but not through the rectal muscularis propria. PET CT showed no perirectal invasion, lymphadenopathy, metastatic disease orother sources of primary SCC. Final staging was T2N0. She underwentchemoradiationwith5-fluorouricil and mitomycin. Surgery was deferred to preserve anal function.Her tumor showed a complete response after 6 weeks and she is currently being followed with routine surveillance. DISCUSSION: Anal SCC makes up2.6% of digestive system cancers in the United States, but its incidence is rising in men and women, possibly due to changes in sexual behavior and increasing rates of HPV exposure. Gastroenterologists should recognizeatypical presentations ofanal SCC, especially in high-risk populations: men who have sex with men, HIV positive patients, and women with high risk HPV. Rectal bleeding and altered bowel habits arethe most commonlyreported symptoms. Other symptoms include anal mass, pain, itching, and mucous discharge, but up to 20% of patients with anal cancer are asymptomatic. The absence of anal pain and external lesions as well as the rectal mass on in our patient suggested an alternative diagnosis. Given that management of rectal cancer has traditionally centered around resection, this emphasizes the utility of EUS to make the correct diagnosis and direct management. The management of this unique presentation of anal SCC has not been fully established, but our patient received standard chemoradiation with good results. Anal SCC has a range of presentations and can present as a rectal mass. Given that anal SCC rates are increasing, our case highlights the importance of disease screening, recognition, and prevention.