Thymoma

Thymoma

CR – Noncalcified mediastinal mass distorting the aorticopulmonary window.

CT – Thin walled uniformly low attenuation anterior mediastinal mass.

Thymomas are very rare tumors in children and adolescents and generally are not even listed in the differential consideration of pediatric mediastinal masses. They are usually discovered incidentally but may be associated with cough, chest pain, dyspnea, dysphagia, hoarseness, recurrent respiratory infection, superior vena cava obstruction or Horner syndrome. The paraneoplastic symptoms frequently associated with thymomas in adults (myasthenia gravis, pure red cell aplasia, polymyositis, systemic lupus erythematosus, rheumatoid arthritis, thyroiditis, and acquired hypogammaglobulinemia) are uncommon in children. Thymomas may present as round, ovoid, or lobulated masses. They are often solid but may have areas of hemorrhage, calcification and/or cystic degeneration. Although most are encapsulated and slow growing, thymomas are occasionally invasive. Histologically benign tumors may have malignant behavior and, conversely, slowly growing tumors may have malignant histology. Prognosis is generally good with complete surgical resection; radiation and chemotherapy are employed with invasive and malignant disease. The incidence of second malignancies in patients with thymoma approaches one in four.

Verhey PT, Hopkins KL, Primack SL, et al. Noninvasive Cystic Thymoma in an Adolescent Boy. AJR (2006); 186(4):1176-1180.