99mTc-methylene diphosphonate uptake by ossifications and calcifications of non-osseous metastatic tumors

Two cases of extra-osseous uptake of 99mTc-methylene diphosphonate (MDP) by non-osseous metastatic tumors are reported. One was a metastasis with ossification in the abdominal wall from carcinoma of the sigmoid colon and the other was a metastasis with calcification from an ovarian carcinoma. The mechanism of extra-osseous uptake of 99mTc-MDP is discussed. Bone scintigraphy can be a potential means to assess tumor spread with ossifications and calcifications.