ABSTRACT
Neurofibromatosis Type 1 (NF1) is a common hereditary disease characterized by disorders regarding the skin, neural, and skeletal systems. Osteoporosis is one of the skeletal manifestations of NF1, which is associated with increased fracture risk. The management of NF1-related low bone mass has been less studied in the literature. We present a 19-year-old patient with severe low bone mass complicating NF1. The patient received 1-year course of 35 mg risedronate sodium once per week along with a daily regimen of 1200 mg calcium and 800 IU vitamin D. Significant improvement with regard to the Z-scores and bone mineral density values was achieved. Besides, rapid favourable biochemical response was obtained. The patient experienced 24·4 and 15·0% improvements in bone mineral density at the lumbar site and hip, respectively, at the first year of therapy. No adverse effect was observed. Since increased bone turnover is the primary contributor of osteoporosis in NF1, antiresorptive agents such as bisphosphonates can be considered for treatment. Despite the lack of consensus on the treatment of osteoporosis in NF1, risedronate may hold a promise as a potential therapy for osteoporosis complicating NF1. This is the first report of risedronate therapy in a case with NF1-associated low bone mass in the literature.