Snapshot A 14-year-old girl presents to the emergency room with acute abdominal pain and constipation. An ultrasound reveals a “target sign”, suggesting intussusception. A CT scan confirms this diagnosis. On closer examination, her palms and oral mucosa are spotted with multiple 1-2 mm blue-gray macules. She is scheduled for emergency surgery to decompress the intussusception with follow-up endoscopy as an outpatient. Introduction Inherited syndrome with multiple, nonmalignant hamartomatous polyps in GI tract mucocutaneous hyperpigmentation Genetics autosomal dominant mutation in STK11 serine threonine kinase tumor suppressor gene Associated conditions ↑ risk for multiple malignancies Presentation Symptoms/physical exam hyperpigmented mucocutaneous macules blue-gray or brown spots most common spots lips and buccal mucosa palms and soles hamartomatous polyps most common in small bowel bowel obstruction intussusception abdominal pain infarction chronic bleeding may be sessile, pedunculated, or lobulated Evaluation Diagnosis with endoscopy histology hamartomas proliferation of smooth muscle into lamina propria Complete blood count iron-deficiency anemia due to blood loss Differential Diagnosis Familial adenomatous polyposis Juvenile polyposis Cowden syndrome Treatment Routine evaluation with cancer screening every 1-2 years Endoscopic resection of polyps if extensive, surgical resection Prognosis, Prevention, and Complications Prognosis high risk of malignant transformation of polyps good with routine screening Complications malignant transformation of macules are rare increased risk of colorectal cancer breast pancreatic stomach gynecologic