Colloid scintigraphy showing red bone marrow extension in patients with prostatic carcinoma

In 25 of 30 patients with bone metastases from prostatic carcinoma, red bone marrow extension was observed by scintigraphy of the reticuloendothelial system (RES). The degree of bone marrow extension in the lower extremities increased with increasing number of bone metastases. In 8 patients, 15 peripheral metastases were detected, all located in areas with extended red bone marrow. The distal level of bone marrow extension coincided with that of the most distal metastases. This is of importance for the detection of peripheral metastases at risk for fracture. Bone marrow extension was also seen in 5 of 8 patients with prostatic carcinoma without bone metastases and was interpreted as a paramalignant activation of RES.