Hyperthyroidism secondary to a primary mediastinal goiter with normal functional cervical thyroid gland.

Primary mediastinal goiter is extremely uncommon. The majority of primary mediastinal goiters were reported as incidental findings on chest imaging of asymptomatic patients. Symptoms related to compression of adjacent structures or hyperthyroidism were rarely described. Herein we report a case of hyperthyroidism secondary to a primary mediastinal goiter.