There are no constitutional symptoms. Examination reveals a tender mass with mild surrounding warmth and erythema, but no fever or adenopathy. Laboratory studies typically show a normal white blood-cell count and differential and a mildly elevated sedementation rate. Electrolytes and other laboratory values are unaffected. Plain radiographs show the tumor is adjacent to the bone rather than arising from it.
Soft tissue swelling is seen as well as a marked periosteal reaction.
There may be new bone formation in the soft tissues and subtle cortical thinning. In rare cases there is local erosion of the cortex. Technetium-99 bone scans show a solitary focus of intense uptake. Magnetic resonance scans show a mass and striking signal abnormalities in the soft tissues as well as the nearby bone marrow that are relatively nonspecific and are consistent with infection, trauma, or tumor. While the lesion is benign, the findings overlap with this of osteosarcoma, infection, and other aggressive lesions.