Treatment of PDGFRB-Related Penttinen Syndrome With Imatinib in a Young Child.

PDGFRB-related Penttinen syndrome is characterized by progressive progeroid features, acroosteolysis, and development of aneurysms, structural anomalies of the posterior fossa, variable myofibromatosis, and overgrowth. PDGFRB-related disorders, including Penttinen syndrome, Kosaki syndrome, and infantile myofibromatosis, have been successfully treated using imatinib. Here, we report a child diagnosed in infancy who initiated imatinib monotherapy at 8 months of age and has continued treatment for 4 years. At the time of diagnosis, he was known to have structural anomalies of the posterior fossa, sparse hair, joint stiffness, myofibromatosis, thin and fragile skin, decreased subcutaneous fat, and prominent vasculature. Imatinib has been well tolerated without apparent side effects. Within weeks to months after initiating imatinib, he grew thick curly hair, and the texture of his skin and joint stiffness had marked improvement. Over the past 4 years, he has not developed acroosteolysis and continues to have normal hair growth. Surveillance MRA has not identified aneurysms or vessel ectasia. Height decreased from 90th to 75th percentile. He has mild developmental delays and is awaiting formal evaluation for autism spectrum disorder. Overall, early imatinib treatment has been successful in ameliorating and preventing the development of some features of Penttinen syndrome.