Overlap syndrome of hereditary hemorrhagic telangiectasia and juvenile polyposis syndrome: ten years follow-up-case series and review of literature.

Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal vascular dysplasia characterized by the presence of mucocutaneous telangiectasia and arteriovenous malformations in solid organs. The Curaçao criteria and/or detection of ALK1, ENG, and SMAD4 gene mutations are used for diagnosis. Juvenile Polyposis Syndrome (JPS) is diagnosed according to the number and localization of juvenile polyps, and family history of JPS. Both entities have a low prevalence. Mutation of SMAD4 leads to a combined syndrome of these two conditions called HHT-JPS Overlap Syndrome. We aim to describe the clinical characteristics associated with this condition focusing on long term follow up and review of the literature. A cross-sectional descriptive study of HHT-JPS cases from an HHT Institutional Registry was designed. Patients were eligible for this case series if they fulfilled both HHT and JPS diagnostic criteria and/or mutation on SMAD4. A comprehensive review was conducted on the clinical phenotype associated with HHT and its gastrointestinal involvement. Fourteen patients from eleven families in 788 previously HHT-diagnosed patients met the inclusion criteria. The ages ranged between 25 and 70 years old and 12 were females. In addition to the typical signs/symptoms of HHT, two distinct phenotypes were observed. Nine patients predominantly exhibited initially upper, while five showed predominantly initially lower gastrointestinal involvement. Numerous musculoskeletal and cardiovascular anomalies were also identified. The observed phenotypic diversity, particularly in gastrointestinal involvement, underscores the need for tailored clinical approaches. Comprehensive assessments identified associated musculoskeletal and cardiovascular anomalies, emphasizing the systemic nature of HHT-JPS.