99mTc-phosphonates for imaging of amyloid in C-cell carcinoma

A patient with recurrent C-cell carcinoma of the thyroid is presented. Tumor masses and metastatic lymph nodes were detected by 99mTc-DPD on a preoperative bone scan. In contrast to other causes of extraosseous accumulation of bone-seeking phosphonates, the high affinity of amyloid is the main factor in the case of C-cell carcinoma. Because amyloid is the typical histochemical sign of the carcinoma type, imaging with phosphonates is expected to be another specific diagnostic procedure in addition to calcitonin measurements. The role of other markers in thyroid carcinomas is discussed.