Bone scintigraphy in nonsurgically treated Ewing's sarcoma at diagnosis and follow-up: prognostic information of the primary tumor site.

In order to detect skeletal metastases in patients with Ewing's sarcoma, bone scanning is commonly used. However, little information is available about the scintigraphic aspects of the primary Ewing's sarcoma during non-surgical treatment and follow-up. We studied retrospectively the significance of bone scintigraphic findings at the primary tumor site of 58 patients with a Ewing's sarcoma. These patients had chemotherapy and radiotherapy. At presentation 53/58 patients showed an increased tracer uptake at the primary tumor site while 5 patients with a pelvic or sacral bone localization had a normal scan. Bone scans made during treatment and more than 2 years thereafter in the 32 eligible patients demonstrated three patterns. In 16 patients the hot spot disappeared and no local tumor recurrence was encountered. In the other 16 patients the high uptake at the primary tumor site either persisted or diminished first to a normal uptake after a median period of 18 months (range 12-36 months) and returned again to a high uptake within 6-12 months. In these patients local Ewing's sarcoma was still present in 13, while in the other 3 cases a benign disorder (fracture, ectopic bone formation) was the underlying cause. These findings suggest that in non-surgically treated Ewing's sarcoma persisting increased tracer uptake or its recurrence is highly suspicious for the presence of Ewing's sarcoma, while bone scans becoming negative and remaining so for more than 12 months suggest the absence of local tumor.