Positron emission tomography in combination with computed tomography with 18F-fluorocholine in the topical diagnosis of parathyroid tumors and secondary changes in bone tissue associated with hyperparathyroid osteodystrophy: two case studies

Primary hyperparathyroidism (PHPT) is caused by parathyroid malignant neoplasm in 1% of cases. The risk of the latter is higher in patients with symptomatic PHPT. The prognosis in this group of patients depends on the extent of the process and primary surgical intervention. In these cases, the differential diagnosis between secondary foci in the bones associated with parathyroid cancer and hyperparathyroid osteodystrophy is a challenging problem. This article describes two cases of severe PHPT accompanied by hyperparathyroid osteodystrophy suspected for metastatic parathyroid cancer. Positron emission tomography in combination with computed tomography (PET/CT) with 18F-fluorodeoxyglucose (18F-FDG) and/or 18F-fluorocholine was included in the examination algorithm. In both cases, pronounced bone changes similar to parathyroid metastases were observed. Accumulation of 18F-fluorocholine was also observed only in altered parathyroid gland. Histological examination of postoperative material verified benign parathyroid tumors, and characteristic lesions of bone tissue were regarded as areas of osteodystrophy. Therefore, accumulation of 18F-fluorocholine at the areas of bone destruction does not enable differentiation between hyperparathyroid osteodystrophy and metastatic lesions; further research is required to assess sensitivity and specificity of the method with respect to topical diagnosis of altered parathyroid gland.