utility of 99mtc-sestamibi spect/ct in the early localization of metastatic parathyroid carcinoma

Parathyroid carcinoma is very rare, with only a few documented cases. hence, metastatic lesions are infrequently documented on scintigraphic imaging. we present a case of a 63-year-old female presenting with elevated serum levels of ionized calcium and parathyroid hormone (pth) who was referred to our department for a parathyroid scan with spect/ ct. parathyroid scintigraphy showed a focus of increased 99mtc-sestamibi uptake corresponding to a solid mass with calcification in the inferior pole of the right thyroid lobe; tracer retention was noted on delayed images. incidentally, focal uptake was also seen in a soft tissue mass on the 7th right rib. the patient soon underwent total thyroidectomy, with biopsy revealing parathyroid carcinoma on the right lobe. a bone scan done 7 months after surgery confirmed the presence of metastatic bone disease. the concomitant detection of intrathyroidal and extrathyroidal sestamibiavid masses on parathyroid scintigraphy should increase clinical suspicion of a metastatic process from parathyroid carcinoma.