Background: Medullary thyroid cancer (MTC) is an uncommon and aggressive tumour representing only 5-10% of all thyroid malignancies. MTC arises from parafollicular thyroid cells (C-cells) producing calcitonin hormone. Differentiated thyroid cancer (DTC) is the most frequent thyroid tumour (papillary or follicular), representing 80% of all thyroid cancer. DTC derives from follicular thyroid cells, that come from the central thyroid sketch. The association between medullary and papillary thyroid cancer is rare. Several cases have been reported of mixed carcinomas.
Case report: We report two cases of associated medullary and papillary carcinomas in two different foci in patients with respectively Graves' disease and multinodular goiter. A young woman affected by Grave's disease and multinodular goiter under pharmacological treatment with antithyroidal drugs underwent total thyroidectomy. The histopathological examination revealed the presence of a medullary carcinoma of the middle third of right lobe (1.1 cm) with an adjacent papillary microcarcinoma (0.5 cm). A 72-years-old woman, affected by euthyroid multinodular goiter, underwent total thyroidectomy. The pathological findings were two microcarcinomas, medullary (0.44 cm) in the left lobe and papillary (0.22 cm) in the right lobe.
Conclusion: We can speculate that this coexistence is inferred, not having shown a specific cause that justifies the association between the two types of tumour and the high prevalence of papillary carcinoma.