ABSTRACT
Background: Type V osteogenesis imperfecta is characterized by hyperplastic callus formation and interosseus membrane calcification. Case characteristics: A 16-year-old boy who presented with history of recurrent fractures, had hard persistent swellings at fracture sites, and had radiographic features of hyperplastic callus and interosseus membrane calcification. Outcome: Sequence analysis of the IFITM5 gene revealed the c.-14 C>T mutation. The patient had significant exacerbation of callus hyperplasia after initiation of bisphosphonate therapy, which reversed following cessation of the treatment. Message: Bisphosphonates may exacerbate callus hyperplasia, and may therefore have to be used with caution in patients with type V osteogenesis imperfecta.