Inflammatory myofibroblastic tumor (inflammatory fibrosarcoma) of the bone.

Although inflammatory myofibroblastic tumors, originally described in the lung, have recently been recognized to occur in various sites, their origin in bone is exceptional. We present a case of inflammatory myofibroblastic tumor, so-called inflammatory fibrosarcoma, of the bone. The tumor occurred in the iliac bone of a 70-year-old woman. Standard radiographs and magnetic resonance imaging revealed a destructive bone tumor that expanded into the soft tissue. Although the patient underwent excision of the hemi-iliac bone, multiple pulmonary metastases were noted 1 year after the operation. On histologic examination, the tumor was found to be composed of a sarcoma-like cellular area and a hypocellular fibrous area. Inflammatory cell infiltration into the tumor was a distinctive feature and is analogous with that of conventional inflammatory myofibroblastic tumor or inflammatory fibrosarcoma of the soft tissue. This is the first report to our knowledge of an inflammatory myofibroblastic tumor of the bone with distant metastasis.