Incidental Diagnosis of Serrated Polyposis Syndrome of the Small and Large Bowel Treated Endoscopically and Surgically: A Case Report.

Colorectal serrated polyps are now recognized as an important pathway in colorectal carcinogenesis. An association between serrated polyposis syndrome (SPS) and duodenal serrated lesions sharing a similar immunophenotype in both the colon and duodenum has been reported in the literature. We present a case of a 38-year-old male who presented in June 2023 with abdominal pain and fever. Initial investigations, including multiple computed tomography scans of the abdomen and pelvis, revealed an appendiceal abscess and small bowel intussusception involving two segments of the jejunum without evidence of obstruction, along with multiple polyps throughout the small and large bowel suggestive of an intestinal polyposis syndrome. Further evaluation with colonoscopy, esophagogastroduodenoscopy, and magnetic resonance enterography confirmed the presence of numerous polyps of varying sizes involving the duodenum, jejunum, ileum, and all segments of the colon. The initial differential diagnosis included familial adenomatous polyposis, Peutz-Jeghers syndrome, and PTEN hamartoma tumor syndrome. The patient subsequently developed complicated small bowel obstruction due to intussusception and underwent open small bowel resection. Multiple intestinal polyps were identified, and histopathological examination confirmed the diagnosis of SPS. At a later stage, the patient was planned for subtotal colectomy, preceded by elective endoscopic polypectomy, which achieved clearance of the left colon up to 20 cm from the anal verge. Gross examination of the colectomy specimen revealed more than 20 large polyps measuring up to 4 cm. Histopathological analysis demonstrated colonic serrated polyposis without evidence of invasive malignancy, wall infiltration, or lymph node involvement, with clear surgical margins.