Parathyroid Cancer

PARATHYROID CANCER:
THE ROLE OF NUCLEAR MEDICINE
KS von Wenzel, A Ellmann, SM Rubow
Nuclear Medicine, Windhoek Central Hospital, Namibia
Nuclear Medicine, Tygerberg Hospital and Stellenbosch University, SA

INTRODUCTION
Parathyroid carcinoma is rare endocrine tumor, occurring in 0,5%-5% of patient with primary hyperparathyroidism. Most patients with parathyroid carcinoma are asymptomatic at the time of presentation, while many patient with benign primary hyperparathyroidism are discovered incidentally during routine biochemical evaluation. Nuclear medicine investigations can be of value in the evaluation of this patients. These include parathyroid scintigraphy for localization of lesions, and skeletal scintigraphy for evaluating for evaluation skeletal Sequelae of the condition.

PARATHYROID GLANDS

CASE REPORT

A 42 year old woman presented with severe bone pain, elevated serum PTH and calcium levels, but normal renal function. She was referred for a parathyroid and a skeletal scintigram. Imaging after administration of Tc-99m MIBI confirmed vague uptake of activity inferior in the right thyroid lobe, which was more prominent on the later views. Then a bone scan showed features of hyperparathyroidism.

A follow up bone scan four months later demonstrated multiple skeletal lesions. At surgery the right inferior parathyroid was resected and a parathyroid carcinoma was confirmed histologically and the patient was treated with chemotherapy.

The serum PTH four months after removal of the primary lesion was still elevated, the cause of this is unknown. On whole body MIBI scan some skeletal lesions concentrated MIBI while others were MIBI negative.

DISCUSSION
Parathyroid scintigraphy cannot distinguish between adenoma and carcinoma as the cause of hyperparathyroidism, except if spread to adjacent soft tissue structures can be detected on the scintigraphy. The skeletal scintigraphy can demonstrate skeletal changes caused by hyperparathyroidism.

Two distinct scintigraphic findings have been associated with hyperparathyroidism, namely the so called “superscan” appearance and soft tissue calcifications secondary to deposition of calcium in soft tissues.

A less common scintigraphic finding is the uptake of Tc-99m MIBI in Brown tumors. They are report in the literature on Brown tumors mimicking metastatic bone disease on skeletal scintigraphy. In this case is unclear whether the skeletal lesions are a mixture of Brown tumors and skeletal metastases, as some lesions concentrated MIBI and others not.

This case report was presented at the 9th World Congress of Nuclear Medicine and Biology in Seoul Korea 2007.

 

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