Long-Term Follow-Up of a Primary Teratoma With Somatic-Type Malignancy Within the Thyroid Gland Mimicking Thyroid Carcinoma

Primary teratoma of the thyroid as an extragonadal germ cell tumor (EGCT) in men is a very rare disease with highly malignant potential and poor prognosis. As a secondary tumor, EGCT after burned out gonadal tumor leaving a fibrous scar can mimic a primary EGCT; accurate staging procedures are always mandatory. This report presents the first case of EGCT in an adult male thyroid gland with long-term disease-free survival (12 years since salvage chemotherapy).