Pseudo-tumoral osteomyelitis. Immunologic study and etiopathogenic approach. Apropos of 2 cases]

Two cases of pseudo-tumoral osteomyelitis are reported. The first concerns a 12 year-old boy who presented with pain of the left knee during 8 months and, later on, with swelling of the upper extremity of the left leg, without fever or local inflammatory signs. The radiological aspect of condensation with a filling defect and "chimney" crossing the cartilage led to osteotomy. Local bacteriological samplings were normal. The second case concerns a 11 year-old boy who, after having complained from pain of the right wrist during 2 weeks, presented with swelling and on X-ray films a picture of metaphyso-epiphyseal lysis and an aspect of sequestrum in its center. There was no biological sign of inflammation. Evolution was favorable after antibiotic treatment and immobilization. In both cases, an immunological study showed an activation syndrome of the immune system with increased serum IL-1, IL-2 receptors and class II antigen receptors on the surface of T cells, suggesting a previous immunization of both children towards staphylococcus and, thereby, the subacute nature of evolution.