P0159 - A Sessile Serrated Adenoma Presenting as Appendicitis in a Young Patient

Rafaela Izurieta, MD¹, Cesar Rosa, DO¹, Charles B. Miller, MD¹, Matthew Uy, DO^2
1San Antonio Uniformed Services Health Education Consortium, Fort Sam Houston, TX; ²San Antonio Uniformed Services Health Education Consortium, San Antonio, TX

Introduction: Neoplasms of the appendix are rare, comprising only 0.4% of gastrointestinal malignancies. And although colorectal sessile serrated adenomas (SSA) are not uncommon, the incidence of SSA within the appendix is unknown, with literature review indicating fewer than 50 reported cases.

Patients with appendiceal neoplasms present most commonly with symptoms of acute appendicitis, and the neoplasm is found on pathology after appendectomy. Appendectomy alone is usually appropriate if negative margins are identified on pathology and if the neoplasm is early grade without angiolymphatic invasion. In the case of an adenoma, patients should also undergo colonoscopy to ensure no residual or synchronous adenomas.

Case Description/Methods: A 22 year old man presented to the emergency department with one day of acute right lower quadrant abdominal pain. CT imaging was significant for appendiceal dilatation with surrounding stranding. He was admitted for appendicitis and underwent appendectomy. Pathology of the excised appendix demonstrated evidence of acute appendicitis as well as an unexpected SSA at the margin. A subsequent colonoscopy demonstrated normal colonic mucosa throughout, and no polyps. The appendiceal orifice (AO) and peri-AO were endoscopically normal under high-definition white light and narrow-band imaging, with no evidence of SSA in extensive biopsies. A multidisciplinary tumor board recommended partial cecectomy based on the involved margins on histology of the initial appendectomy. He underwent an uneventful resection, and pathology confirmed no residual SSA in the specimen.

Discussion: Interestingly, this uncommon presentation occurred in a patient with none of the usual risk factors for SSA; he denied alcohol or tobacco use, had a normal BMI, and his age was well outside the usual age range of incidence. Additionally, he had no family history of colon polyps or colorectal cancer, though this may be less relevant for SSA, in particular.

In this young patient, the decision for partial cecectomy was made through a multidisciplinary tumor board. The initial appendectomy sample did not yield clear margins, and despite appropriate endoscopic imaging and biopsy samples without evidence of SSA, the decision was to proceed with partial cecectomy, to ensure no residual adenoma. As no further adenoma was identified, the patient will undergo a surveillance colonoscopy in five years to exclude adenomas in the remaining colon.


Figure: A. H&E; 2x objective; Low power view of the appendix cross section shows a sessile serrated lesion with dilation/distortion at the base of the crypts on the left (arrows).
B. H&E; 10x objective; Section of appendix with sessile serrated lesion demonstrating the characteristic “boot-shaped” crypts.
C. CT abdomen/pelvis demonstrating uncomplicated acute appendicitis. The appendix is dilated with maximal diameter up to 1.2 cm with small amount of hyperdense material at the base, and associated periappendiceal fat stranding and fluid/fat stranding about the appendix.
D. Endoscopic image, white light, around the appendiceal orifice/cecum demonstrating no adenoma.
E. Endoscopic image, narrow band imaging, around the appendiceal orifice/cecum demonstrating no adenoma.


Disclosures:
Rafaela Izurieta indicated no relevant financial relationships.
Cesar Rosa indicated no relevant financial relationships.
Charles Miller indicated no relevant financial relationships.
Matthew Uy indicated no relevant financial relationships.


Rafaela Izurieta, MD¹, Cesar Rosa, DO¹, Charles B. Miller, MD¹, Matthew Uy, DO². P0159 - A Sessile Serrated Adenoma Presenting as Appendicitis in a Young Patient, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.