Non-osseous bone scan abnormalities in multiple myeloma associated with hypercalcemia.

Uptake of Tc-99m MDP by extraskeletal tissues is a rare, serendipitous finding during bone scanning studies. It can be clinically correlated with the presence of hypercalcemia in association with renal failure, as may occur in multiple myeloma. While the precise mechanism of non-osseous uptake of MDP is not certain, it may represent metastatic calcification based upon histological examination. A critical calcium-phosphate ion product appears to be requisite for deposition within soft tissues, and all cases in the literature for which data were available exceeded this ion product value. While MDP bone scanning is not generally useful in the diagnosis or staging of multiple myeloma, these findings may indicate secondary effects of the disease. The authors report the first case of liver, spleen, and lung uptake by MDP in a patient with hypercalcemia secondary to multiple myeloma, with a review of the literature.