Osteoblastic bone metastases in medullary thyroid carcinoma.

We report on a 32-year-old medullary thyroid carcinoma patient with extensive metastases at the time of diagnosis. In contrast to the osteolytic metastases usually observed in thyroid carcinoma, the patient had osteoblastic bone metastases, assumed to be caused by biologically active tumor calcitonin. The patient died 15 years after initial diagnosis of the advanced tumor. The long survival time may indicate that the prognosis is better for osteoblastic metastases than for osteolytic metastases.