The discovery of a partially calcified anterior mediastinal mass broadens the differential diagnosis (Table 1). Thymoma is the most common primary tumor of the anterior mediastinum seen equally among men and women usually aged >40 years.7,8 Although typically asymptomatic, 30% to 50% of patients with thymoma present with myasthenia gravis confirmed by elevated serum antiacetylcholine receptor antibody. Less frequently, patients demonstrate hypogammaglobulinemia (10% of patients) or pure red cell aplasia (5%).8 Thymic carcinoma is an aggressive malignancy that comprises 20% of all thymic epithelial tumors seen in patients with a mean age of 50 years.8,9 Distant metastases are present at diagnosis in 50% to 65% of patients with thymic carcinoma. More uncommon is thymic carcinoid, a low-grade malignant neuroendocrine tumor seen in three times as many men as women, with greatest frequency in the fourth and fifth decades of life.8,9 Thymic carcinoid is associated with endocrine abnormalities such as Cushing syndrome in 25% to 40% of patients and multiple endocrine neoplasia syndromes I or II in 20% of cases. Lymphoma is one of the most common neoplasms of the mediastinum, although it is infrequently limited to the mediastinum at diagnosis. The nodular sclerosing subtype of Hodgkin’s disease has a predilection for the anterior mediastinum, presenting as a discrete bulky soft tissue mass.10 However, calcification in lymphoma is rare without prior therapy. Similarly, calcified metastatic adenopathy confined to the anterior mediastinum would be unusual, especially in the absence of known malignancy. Castleman disease, or giant lymph node hyperplasia, is an uncommon entity that involves the thorax in 70% of patients, most frequently the mediastinum.11,12 Whether localized or multifocal, the disease often is asymptomatic, with a peak incidence in the fourth decade of life. Germ-cell tumors produce 10% to 15% of anterior mediastinal tumors in adults, more frequently among young adults in the third decade of life.8,13 These tumors usually are mature teratomas that comprise 60% to 70% of germ-cell tumors and are seen equally in men and women.13 Uncommonly, malignant germ-cell tumors, such as seminoma, may produce calcification. However, the majority of patients with seminoma are young adult men, and β-human chorionic gonadotropin levels often are elevated.7,8,14 Finally, an enlarged thyroid goiter may descend into the anterior mediastinum, although an enlarged or nodular thyroid gland would probably be felt during physical examination.