Oncocytic variant of medullary thyroid carcinoma: a rare case of sporadic multifocal and bilateral RET-wild type neoplasm with revision of the literature

Oncocytic variant of medullary thyroid carcinoma (OV-MTC) is a very unusual entity, up to date only 17 cases have been reported in the literature. MTC is a neuro-endocrine malignancy arising from the para-follicular C cells of the thyroid gland. It generally has a slight female predominance and appears as a single lesion. However in the Multiple Endocrine Neoplasia Syndrome 2, linked to the point mutation of RET oncogene, multifocal MTCs may also occur. Herein, we report the case of a 75 years old man with a rare form of sporadic multifocal and bilateral OV-MTC expressing wild-type RET gene. The histological and molecular features of this rare entity are presented and discussed with revision of the pertinent literature.