[Familial medullary thyroid carcinoma: case report and literature review.].

Medullary thyroid carcinoma (MTC) is a malignant tumour of the calcitonin-secreting parafollicular C cells of the thyroid gland. Up to 25% of MTC are associated to pathogenic germinal variants on the proto-oncogene RET (locus 10q11.2), which cause Familial Medullary Thyroid Carcinoma (FMTC) or Multiple Endocrine Neoplasia type 2 (MEN2); genetic conditions inherited with autosomal dominant pattern.