Safe Continuation of Pegvisomant During Pregnancy in a Patient With Fibrous Dysplasia/McCune-Albright Syndrome

Fibrous dysplasia/McCune-Albright syndrome (FD/MAS) is a rare genetic disorder resulting from a postzygotic activating mutation of the GNAS gene, leading to mosaic activation of the G_s protein. FD/MAS encompasses skeletal and extraskeletal manifestations, including GH excess. Medical management of GH excess in FD/MAS can be complex, especially during pregnancy, due to limited safety data on pharmacotherapy. We describe a 31-year-old female with FD/MAS who continued pegvisomant for a GH and prolactin cosecreting pituitary adenoma during her pregnancy to minimize the risk of GH-induced craniofacial fibrous dysplasia progression and consequent visual loss. She had an uncomplicated pregnancy with delivery of a healthy baby girl at term. This case demonstrates safe and efficacious use of pegvisomant in managing GH excess during pregnancy and is the first report in an individual with FD/MAS, underscoring its potential role in similar cases.