Sessile Serrated Adenoma With Submucosal Lipoma: Should Colonoscopy Be Repeated Sooner?

Abstract

A 60-year-old man with history of colorectal polyps 10 years ago presented to the gastroenterology clinic to discuss colorectal cancer screening. Review of systems was notable for occasional blood mixed with stools. Physical examination was unremarkable other than external hemorrhoids. During the colonoscopy, a 1.4 cm polypoid shaped sessile polyp was found in the proximal ascending colon (Figure A) which was injected at its base with epinephrine prior to cold snare polypectomy (Figure B). Colonoscopy and pathology further revealed mild left sided diverticulosis, medium external hemorrhoids, a 0.3 cm tubular adenomatous polyp in the transverse colon, a 1.4 cm sessile serrated polyp overlying a submucosal lipoma in the proximal ascending colon (Figure C), a 0.3 cm hyperplastic polyp in the sigmoid colon, a 0.4 cm sessile serrated polyp in the rectosigmoid colon, and a 0.3 cm tubular adenomatous polyp in the rectum. Patient was notified to have a repeat colonoscopy done in 3 years. Sessile serrated adenomas/polyps (SSA/Ps) are pre-cancerous lesions that account for 5-25% of serrated lesions. The overall prevalence of submucosal lipomas in association with SSA/Ps are not as well studied, but one study showed 17.7% of SSA/Ps identified in the authors' practice had submucosal lipomas as opposed to 2.7% of tubular adenomas (TAs) with submucosal lipomas. Given that SSA/Ps progress to cancer through a different mechanism than TAs, this noted association with submucosal lipomas may represent an interaction but the epithelium and mesenchyme. Being aware of a possible association of SSA/Ps with submucosal lipomas is important knowledge for the endoscopist to not misdiagnose the lesion as a perforation. Furthermore, there was an association found between the presence of submucosal lipomas and more numerous SSA/Ps and more dysplastic SSA/Ps. Further molecular and genetic studies need to be done in order to further elucidate the relationship between submucosal lipomas and SSA/Ps. Ensuring patients adhere to recommended colonoscopy screening intervals would ensure a patient like this one does not progress to colorectal cancer. If a clear association were to be made between submucosal lipomas and worse outcomes when seen with SSA/P, then there may be a role for adjusting surveillance intervals.Figure: Proximal ascending colon polypoid shaped sessile polyp measuring 1.4 cm.Figure: Post-polypectomy defect with fatty adipose tissue present in removed tissue.Figure: SSA histology with underlying submucosal lipoma.