A mediastinal lipoma is an unusual, but benign tumor composed of a large amount of mature adipose tissue within the mediastinum. It represents less than 1% of all primary mediastinal tumors, and occurs most commonly in the anterior mediastinum. Most patients are asymptomatic; however, retrosternal pain, dry cough or dyspnea may occur due to its mass effect. Because of the slow growth of the mediastinal lipoma, surgical excision should be performed when symptoms present or when the diagnosis is ambiguous using radiographic examinations.