S6098 Peutz-Jeghers Syndrome Disguised as Celiac Disease

Introduction: Peutz-Jeghers syndrome (PJS) is an autosomal dominant disorder characterized by the development of benign hamartomatous polyps throughout the gastrointestinal (GI) tract, typically beginning in childhood. By early adulthood, the polyp burden may cause abdominal pain, GI bleeding, intussusception, or bowel obstruction. Early detection is essential as PJS is associated with a markedly increased risk of various extra-intestinal malignancies. We present a case of PJS misdiagnosed as celiac disease (CD) in an adult patient. Case Description/Methods: A 34-year-old White woman presented for outpatient evaluation of abdominal pain, watery diarrhea, and unintentional weight loss. Serology detected CD-specific antibodies. Endoscopic evaluation was scheduled, but she was hospitalized with severe abdominal pain, new-onset nausea, and emesis soon after the clinic visit. She reported no family history of CD, inflammatory bowel disease, or GI malignancies. She was clinically stable, and labs were grossly normal. Imaging revealed a partial small bowel obstruction proximal to a focal area of marked wall thickening with a mass-like quality. CEA, CA19-9, and chromogranin A were negative. The general surgery team recommended small bowel resection. Intraoperative findings revealed multiple masses (1-2 cm in size) in the distal jejunum, causing intussusception. The lesions were resected, and pathology revealed Peutz-Jeghers hamartomas. Biopsies of the duodenum and repeat CD serologies were negative. An STK11 mutation was not detected on genetic testing. Discussion: PJS is typically identified in childhood by mucocutaneous hyperpigmentation and GI symptoms; however, this patient’s clinical presentation and falsely positive CD serology delayed her true diagnosis. Beyond pathology, patients should undergo genetic testing for the STK11 gene variant. Like our patient, some may lack detectable STK11 gene mutations but still meet clinical criteria. This may be explained by technical limitations or somatic mosaicism. Treatment focuses on early cancer screening and complication management.