Endocrine Abstracts

We describe a case of a 59-years old man, in whom a thyroid nodule with a size of 16 mm and an elevated serum calcitonin level 29 ng/l (upper limit 21 ng/l) was incidentally found. The size of a nodule did not increase in time, serum level of calcitonin was stable and cytology from the nodule was benign. In January 2016, calcium stimulation test was performed with a positive result (baseline calcitonin 31.5 ng/l, stimulated calcitonin 417 ng/l), CEA was low. The patient was refered for thyroidectomy and after the surgery calcitonin level decreased to normal values, calcium test was negative. Histology revealed focal lymphocytic thyroiditis with macrofolicular hyperplastic nodule with regressive changes. Imunohistochemistry detected diffuse and locally nodular hyperplasia of C-cells with a strong expression of calcitonin.

Conclusion: C-cell hyperplasia with an increased secretion of calcitonin is considered to be a preneoplastic lesion associated with a medullary carcinoma of a thyroid gland. Its occurence can be sporadic, or familial in isolated forms or as a part of MEN syndrome. In our case, calcium stimulation test was helpful in differential diagnosis of an elevation of calcitonin of unknown etiology.