Sessile Serrated Adenomas: A Case Presentation Kevin Witt, PGY3 Justin Whitt, MD IU Health Ball Memorial Family Medicine Residency

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Introduction Sessile serrated adenomas (SSAs) of the colon are a challenging entity in colon cancer screening due to subtle morphological features. Endoscopic differentiation between SSAs and more benign lesions is difficult. SSAs are also more common than benign traditional serrated adenomas (TSAs) and are premalignant 1. Endoscopic recognition of these lesions is important for effective colon cancer screening and prevention.

Case A 52 year-old male with no family history of colon cancer presented for routine screening by colonoscopy. Procedure performed via routine, cecum successfully identified. An Olympus 160L Model Colonoscopy was used (no narrow or high-band imaging) An irregular fold without mucosal irregularity in the hepatic flexure was identified and a biopsy was obtained. A 7x9mm adenomatous-appearing polyp was identified and removed from the distal transverse colon. Pathologic analysis demonstrated sessile serrated features of both lesions (the irregular fold at the hepatic flexure and the polyp); however the polyp demonstrated features of high-grade dysplasia.

Case f/u  Due to the uncertainty in size of the lesion at the hepatic flexure, and the polyp with SSA/HGD, the pt was categorized as high risk for colon cancer.  After discussion w/ the pt, he was ultimately referred to GI for evaluation.

 Repeat colonoscopy was performed w/ multiple polyps/polypectomy  4x polypectomies performed. The largest was 15mm at the hepatic flexure  The 15 mm polyp showed SSA features w/out high grade dysplasia  The remainder (3-4 mm polyps) were tubular adenomas

 Repeat colonoscopy in 1 year was recommended due to number of polyps and previous SSA w/ high grade dysplasia

Endoscopic Features of SSAs 1,2 Pale Color Flat or sessile shape Indistinct edges Mucus cap Debris on edges or center No surface vessels/few lacy vessels Surface texture and pits vary from normal Type “O” Pits

Discussion Detection and removal of precancerous lesions on screening colonoscopy is key in colon cancer prevention. SSAs can be insidious and difficult to detect with basic optical colonoscopy. Histologic diagnosis of SSA is also difficult. Accurate diagnosis of SSA and TSA was the lowest among all categories tested 5.

Conclusion Sessile serrated adenomas account for one-third of all sporadic colorectal cancers and are the main precursor lesion in serrated carcinogenesis. Perhaps advanced imaging, such as narrow-band or hi- definition optics, during colonoscopy should be more commonly utilized in order to better identify these precancerous lesions.

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