- Six patients with subacute diaphyseal osteomyelitis of 200 with acute osteomyelitis who were seen and treated at the Red Cross Children's Hospital in a 3-year period (1985-1987) are reported. All six patients had a history of a minimum of 2 weeks' duration and the radiographic picture of a linear periosteal reaction, which was either single or laminated. This radiographic picture was indistinguishable from round cell tumors of bone. The final diagnosis was established by a histology consistent with a subacute osteomyelitis. In two patients, a positive culture of Staphylococcus aureus was obtained. All of the patients healed after treatment with cloxacillin. Radiographic resolution was noted in all patients within 6 months of treatment.