The role of bone scans in assessing malignant melanoma in patients with stage III disease.

Two hundred abnormal bone scans of patients with a malignant melanoma were reread in a blinded fashion to identify osseous metastases. These findings were compared with serum calcium and alkaline phosphatase levels, skeletal surveys and survival curves of the same patients. Thirty-four of the 38 patients classified as positive for osseous metastases by bone scans ultimately supported that diagnosis. Three patients have probable, but not proved, osseous metastases, and one patient is classified as false-positive. Identification of osseous metastases by skeletal surveys never preceded bone scan identification. Skeletal surveys were most helpful in the identification of a benign condition which caused scan positivity. Serum calcium and alkaline phosphatase levels were never as sensitive or specific as either scans or surveys. In two patients with progressive osseous disease, the levels fell. We believe that radionuclide bone scans should be the first diagnostic procedure for suspected osseous metastases in patients with a malignant melanoma. It appears to be a more sensitive and specific test than skeletal surveys or serum calcium and alkaline phosphatase levels. We believe its use as a first test would save time, money and needless surgical procedures.