Giant cell reaction of a metatarsal bone: a case report.

A rare, non-neoplastic lesion involving the 1st metatarsal bone in a 5-year-old female is described. Radiographically it presented as a cystic lesion of the whole of the metatarsal. Fine needle aspiration cytology showed it to be a benign giant cell lesion. The tumour was excised en bloc and the metatarsal replaced by a free fibular graft of adequate length. Histopathological examination confirmed the diagnosis as giant cell reaction of bone. The lesion is said to arise as a local tissue response to bleeding as evidenced by the clustering of giant cells in areas of haemorrhage. The entity should be differentiated from aneurismal bone cyst, brown tumours of hyperparathyroidism giant cell tumour, chondroblastoma, non-ossifying fibroma etc. Treatment usually consists of curettage or excision of the involved bone with or without bone grafting. Recurrences are common in curetted lesions.