Endocrine Abstracts

Parathyroid carcinoma is a rare neuroendocrine tumor, responsible for less than 1% of all cases of primary hyperparathyroidism. The sole curative treatment is complete surgical removal and thus, an accurate preoperative diagnosis is necessary. Due to the rarity of this disease, there is no staging guidelines. Imaging of parathyroid glands is usually obtained with ultrasonography, computed tomography, scintigraphy and positron emission tomography. These imaging modalities have been used and described for parathyroid adenomas. However, there is only limited data on their use in parathyroid carcinoma. On a 51-year-old-woman presenting with severe hypercalcaemia suspicious of parathyroid carcinoma, we performed different imaging studies and we compared the results with histology. 99mTc-sestamibi scintigraphy showed a lesion in the left inferior parathyroid gland and a pathological left thyroid nodule. 11C-methionine PET/CT and 18F-choline PET/CT detected additional lesion in the right inferior parathyroid gland and one left submaxillary lymphnode. The lesions showed a higher uptake of 18F-choline than of 11C-methionine. 18FDG Pet/CT missed both lesions in the inferior parathyroid glands and showed a slight hypermetabolism in the left submaxillary lymphnode. After surgery, histology confirmed the presence of a multifocal parathyroid carcinoma, as shown by 11C-methionine PET/CT and 18F-choline PET/CT. In this case, 18FDG Pet/CT was not useful. In conclusion, 11C-methionine PET/CT and 18F-choline PET/CT should be considered for parathyroid carcinoma staging.