We describe a case of a 58-year-old woman who was diagnosed as having primary NET thyroid with normal calcitonin levels and Ga DOTANOC PET-CT scan findings which were done for initial extent evaluation of the disease.
Even if calcitonin elevation is strongly associated to MTC, it can also be found increased in many pathological different conditions as pregnancy, lactation, C-cells hyperplasia, autoimmune thyroiditis, end stage renal disease, lung and prostate cancer and several neuroendocrine tumours.
These tumors have similar cytologic features and immunohistochemical profile to medullary thyroid carcinoma and thus it is difficult to distinguish them, especially when calcitonin-secreting neuroendocrine tumors are intermediate or higher grade and there is a mass lesion in the thyroid gland.
Medullary thyroid cancer (MTC) is a relatively uncommon neuroendocrine tumor that arises from the calcitonin-secreting parafollicular cells of the thyroid gland.