ENT Case 1

•Diagnosis: Medullary carcinoma of thyroid

•2% of thyroid malignancies, and 8% of thyroid cancer-related deaths

•25% of MTCs are hereditary, autosomal dominant germline gain-of-function mutation in RET proto-oncogene, indicating MEN2A or MEN2B.

•Hereditary isolated MTC, formerly known as familial MTC is a variant of MEN2A

•The etiology of sporadic MTC is unknown

•Recently, histologic grading scheme has been proposed: high-grade MTCs are defined as tumors with at least one of the following three features: mitotic count ≥5 per 2 mm2, Ki67 proliferation index ≥5%, and/or tumour necrosis