A rare presentation and diagnosis of juvenile polyposis syndrome and hereditary hemorrhagic telangiectasia overlap syndrome

We present a unique case of juvenile polyposis and hereditary hemorrhagic telangiectasia overlap syndrome. The patient was found to have polyps on colonoscopy leading to genetic testing revealing an SMAD4 mutation. In children with SMAD4 mutation and juvenile polyposis, this overlap syndrome needs to be considered in the differential diagnosis and prompt the clinician to look for telangiectasias on examination and consider surveillance imaging to look for arteriovenous malformations. Our case highlights this clinical relationship and shows how nontraditional imaging using computed tomography colonography (CTC) can provide complimentary information along with colonoscopy. Despite low-dose techniques, CTC does add a radiation burden in the evaluation of these children who are at high risk for malignancy and should be used cautiously.