Dr. S. Lam
Respiratory Medicine, VGH
Thymomas are rare neoplasms that arise from tissue elements of the thymus and develop in the anterior mediastinum. Other anterior mediastinal tumours such as lymphoma, germ cell tumours and carcinoid tumours should be treated with protocols specific to that type.
Most thymomas are slow-growing tumours with a tendency to recur locally and seldom metastasise hematogenously. The majority of cases are cured. When thymoma is fatal, death is often caused by cardiorespiratory problems resulting from pericardial and pleural metastases.
Encapsulated thymic tumours are usually asymptomatic. Patients with invasive tumours may develop symptoms from a mediastinal mass. Compression of the trachea, bronchus, or lung may result in chest pain, cough or dyspnea. Thymomas can be associated with a variety of clinical syndromes such as myasthenia gravis, pure red cell aplasia, pancytopenia, hypogammaglobulinemia, collagen vascular disease and endocrinopathies. The frequency of association of myasthenia gravis and thymoma depends on selection factors associated with the series. It is estimated that 10% of patients with myasthenia gravis have thymoma and 30% of patients with thymoma have myasthenia gravis. Associated syndromes may but do not always improve with remission of the thymoma.
(Updated May 2001)