Medullary Thyroid Carcinoma, Misdiagnosed as Subacute Thyroiditis and Role of Calcitonin Measurement

The thyroid nodules are found often in the clinical practice in adults. The clinical importance of thyroid nodules is to exclude thyroid cancer, which occurs in 7-15 % of cases with thyroid nodules depending on age, sex, radiation exposure history, family history and other factors. We present a clinical case, misdiagnosed as a subacute thyroiditis, in which the lack of clinical doubt for suspecting the thyroid cancer, despite the negative result of fine needle aspiration biopsy of thyroid nodule and not measuring the calcitonin level, did not allow the diagnosis of medullary thyroid carcinoma (MTC). Based on this clinical case and also the review of literature, we recommend the routine measurement of calcitonin in screening the thyroid nodules, for the early diagnosis of the medullary thyroid carcinoma. Despite the negative result for malignancy of fine needle aspiration biopsy (FNA) of nodule, if the nodule has some echographic signs, characteristic of malignancy, the thyroid surgery must be recommended. Keywords: Medullary thyroid carcinoma, calcitonin, fine needle aspiration biopsy.