Overlap of Juvenile polyposis syndrome and Cowden syndrome due to de novo chromosome 10 deletion involving BMPR1A and PTEN: implications for treatment and surveillance.

We describe a patient with a severe juvenile polyposis phenotype, due to a de novo deletion of chromosome 10q22.3-q24.1. He was initially diagnosed with Juvenile polyposis syndrome (JPS) at age four after presenting with hematochezia due to multiple colonic juvenile polyps. He then re-presented at 23 years with recurrent hematochezia from juvenile polyps in his ileoanal pouch. He is one of the earliest reported cases of JPS associated with a large deletion of chromosome 10. Since his initial diagnosis of JPS further studies have confirmed an association between JPS and mutations in BMPR1A in chromosome band 10q23.2, which is in close proximity to PTEN. Mutations in PTEN cause Cowden syndrome (CS) and other PTEN hamartoma tumor syndromes. Due to the chromosome 10 deletion involving contiguous portions of BMPR1A and PTEN in our patient, he may be at risk for CS associated cancers and features, in addition to the polyps associated with JPS. This case presents new challenges in developing appropriate surveillance algorithms to account for the risks associated with each syndrome and highlights the importance of longitudinal follow-up and transitional care between pediatric and adult gastroenterology for patients with hereditary polyposis syndromes.