Epidemiology
- Most common cause of anterior mediastinal mass in adults
- Age: usually develop between 40-60 y/o
- Sex: occur equally among men and women
- Associated With:
- Myocarditis
- Hypogammaglobulinemia
- Cushing s Syndrome
- Megaesophagus
- Myasthenia Gravis:
- Pure Red Cell Aplasia:
Physiology
- Typically develop adjacent to the junction of the heart and great vessels and tend to be round or oval in shape with relatively smooth margins
- Myasthenia Gravis: the mechanism of thymoma-related myasthenia gravis is thought to be thymic production of autoantibodies directed at acetylcholine receptors
Diagnosis
- CXR/Chest CT patterns
- I131 Scan: negative (excludes thyroid as cause of an anterior mediastinal mass)
Clinical
Symptoms/Signs:
-Sixty percent of patients may be asymptomatic at time of diagnosis; other vague symptoms include cough, dyspnea, and/or chest pain
-Malignancy is best defined by the degree of invasiveness found at surgery, not by histologic appearance
-Benign thymomas (55% to 65%) are contained within a thick fibrous capsule and are cured at time of surgical remova
-Myasthenia Gravis: occurs in 10% to 50% of patients with thymomas, either benign or malignant
-Pure Red Cell Aplasia:
–About 50% of patients with pure red cell aplasia have a thymoma
–Only 5% of patients with thymoma have pure red cell aplasia.
Treatment
- Malignant Thymoma: invade through the capsule and spread locally, and are treated with surgery followed by postoperative radiation
- Thymectomy may induce remission of Pure Red Cell Aplasia in 50% of cases and improvement in Myasthenia Gravis
References
- xxx