Abdominal-wall myositis secondary to intra-arterial chemotherapy for femoral osteosarcoma.

With the increasing application of intra-arterial chemotherapy (IAC), new side-effects are encountered. We describe two children with proximal femoral osteosarcoma who developed focal myositis of the abdominal wall musculature after IAC. In both cases, myositis presented as abdominal pain and mimicked acute abdomen. US demonstrated asymmetrical thickening of abdominal-wall musculature in the right lower abdomen. This diagnosis should be considered when evaluating the patient with unexplained abdominal pain and a history of IAC.