EP1054 - Subepithelial Lesions of the Rectum: Not Just Another type of Polyp

Purpose/Background: Subepithelial lesions of the rectum (SEL), previously known as submucosal lesions are being more frequently detected due to screening colonoscopy and other imaging modalities. Frequently asymptomatic, they present as a bulging into the rectum covered with normal appearing mucosa. They have a wide differential diagnosis including Neuroendocrine tumors (NET), lipoma, leiomyoma, lymphoma, GIST, extrinsic compression and several others. Their macroscopic appearance although suggestive in some cases (NET, lypoma) is insufficient to establish a specific diagnosis and traditional excision techniques frequently fail to remove the whole lesion, establish a histological diagnosis and pose a risk of perforation. The ACG guidelines rely mainly on EUS with FNA or core biopsy followed by either ESD, EMR or surgery. EUS has a significant cost, provides information regarding the lesion and involved layers (which can also be determined with MRI), fails to evaluate the rest of pelvis. FNA is not always possible and small sample size does not allow mitotic count and other pathology requirements. Core needle biopsy is rarely possible in small lesions. And a third intervention would be required to remove lesion. As Colorectal Surgeons, we can obtain the layer information provided by EUS using MRI and if no contraindication is found for small rectal SEL an excisional biopsy may be conducted with the use of TAMIS.

Methods/Interventions: We present the case of a 57 yo male who underwent colonoscopy for chronic diarrhea and screening. At 16 cm from anal verge a 1.8 x 1.2 cm subepithelial lesion was noticed (Image 1), biopsies of the overlying mucosa were performed, and no further attempt was made at resection due to the location, size and risk of intraperitoneal perforation. Pathology report of the mucosa was nonspecific colitis. An MRI showed no other abnormalities and described it as a possible lipoma (Image 2). Patient was scheduled for TAMIS excisional biopsy.

Results/Outcomes: A TAMIS procedure was performed confirming the subepithelial lesion at 16 cm, a full thickness resection was conducted with closure of the defect. His postoperative course was uneventful and was discharged on POD 2.

Pathology report confirmed a completely excised lipoma.

Conclusion/Discussion: SEL despite rare are being encountered more frequently, their management differs from the traditional polyp and a clear diagnostic and therapeutic algorithm must be established. Awareness of the differential diagnosis and management strategies is crucial. Gastroenterologists have relied on EUS and FNA requiring posterior ESD, EMR or surgery Colorectal surgeons have the option of performing MRI and TAMIS as an excisional biopsy for small SEL of rectum, providing a superior tissue sample, the possibility of using both hands, energy devices and even suturing when necessary. This approach has the potential to be both diagnostic and therapeutic, decreasing cost and possibly improving outcomes. We believe further research should be conducted for this purpose.

SEL rectum colonoscopy at 16 cm from anal verge
SEL MRI