A bone cyst treated with corticosteroid installation in an osteopetrotic child.

Bone cysts in patients suffering from osteopetrosis are uncommon. A pathologic fracture might cause therapeutic difficulties because of the osteosclerotic bone. We describe a patient with an autosomal dominant osteopetrosis suffering from a large bone cyst in the proximal femur. The cyst was treated with local injections of corticosteroid and healed completely after 2 injections. To our knowledge, this is the first time that the occurrence of bone cysts has been reported in osteopetrotic patients, which responds effectively and lastingly to steroid injection.