Subacute osteomyelitis presenting as a bone tumour. A review of 21 cases.

Twenty-one patients with subacute osteomyelitis who were initially considered to have bone tumours were reviewed, with an average follow up of 3 years. The clinical symptoms were not specific and laboratory investigations were normal. The radiographic findings were limited osteolysis surrounded by bone sclerosis in 14 cases, osteolysis without definite borders in 6, and onion-layer periosteal bone formation in one. The preoperative diagnoses included osteoid osteoma, osteosarcoma, chondroblastoma, Ewing's sarcoma, giant cell tumour, fibrosarcoma, eosinophilic granuloma, and bone tumour of unknown aetiology. The definitive diagnosis was made by surgical biopsy, histology and cultures which grew staphylococcus in 9 cases. The gross specimens all showed lymphocytes, plasma cells and granulation tissue with osteogenesis. All the patients recovered completely; 17 were treated with antibiotics and immobilisation, and 4 did not need an antibiotic. There was no recurrence of infection after curettage and excision of the infected tissues.