Thymoma is the medical term for a tumor of the thymus ( German also called sweetbreads ). Approximately three quarters of these tumors are benign, and only a quarter is malignant. The malignant thymoma or thymic carcinoma are called malignant.


Approximately 30 % of patients are asymptomatic at the time of diagnosis. Symptoms may include coughing, his feeling of pressure in the chest or shortness of breath.

Occasionally, noticed a thymoma also by a paraneoplastic syndrome. In 25% of all thymomas there is a myasthenia gravis, but also a polymyositis, arthritis or Sjogren's syndrome, red cell aplasia, a giant cell myocarditis, hypogammaglobulinemia, autoimmune movement disorders and other autoimmune diseases may occur. The cause is often a lack of expression of the genes autoimmune regulator ( AIRE ) that amplifies the normal elimination of autoreactive T lymphocytes in the thymus.


Evidence of a thymoma are already produced in the radiograph of the chest. The standard diagnostics include computed tomography ( CT). To differentiate between benign and malignant tumors, the removal of a tissue sample (biopsy ) and their tissue examination is always necessary.

In the WHO classification is subdivided according to the morphological appearance of epithelial cells:

  • Type A - the epithelial cells are predominantly oval or spindle-shaped and resemble the normal medullary epithelial cells of the thymus
  • Type B - the epithelial cells are mainly round or polygonal and resemble the normal cortical epithelial cells of the thymus. After cytological atypia strength of the types B1, B2 and B3 still be distinguished.