Hashimoto's thyroiditis and medullary carcinoma in the same gland : a purely random ocurrence ?

In this paper the authors describe the case of 64-year-old woman who had been suffering from poorly defined thyroid disease for 30 years and Hashimoto's thyroiditis for 3 years, with recent detection of high serum calcitonin and CEA. Her family history was negative for endocrinological diseases and her general medical history was not significant for any diseases, except for mild hypertension. There were no pathological findings at physical examination. Cervical ultrasound showed 2 nodular lesions of the right lobe of the thyroid and the isthmus. FNABs of these nodules were performed under ultrasound control and proved non-diagnostic. The patient underwent total thyroidectomy. Intra-operative frozen sections were negative for cancer. Definitive histological examination was positive for medullary carcinoma of the right thyroid lobe (diameter 0.6 cm) in Hashimoto's thyroiditis. The association between thyroid cancers deriving from follicular cells and Hashimoto's thyroiditis is documented in the literature and would appear to determine a better prognosis. Cases such as the one presented in this paper, however, are rare and it is debated whether lymphocyte infiltration may predispose to the onset of medullary carcinoma or whether it is a defence against the tumour.