Spiculated reactive periosteal bone is usually found in cases of primary ma
lignant bone tumors; rarely in secondary bone lesions. The authors report a
case of bone tumor of the clavicle in a 62 year-old patient with "sunburst
" periosteal reaction on radiographs. The metastatic nature of this lesion
from an unknown prostate carcinoma was confirmed by immunohistochemical stu
dies of the clavicle biopsy. Tumorectomy was performed and the patient's st
atus is stable with a follow-up of 10 months.