Thymic Tumors

Abstract

• Thymic tumours are relatively rare neoplasms with an incidence of 0.15/100,000 population per year in the United States.

• Up 40% of thymoma patients present with no symptoms. Common signs and symptoms are caused by local invasion of the disease or paraneoplastic syndrome especially myasthenia gravis: ~15% patients with myasthenia gravis has thymoma, and ~45% thymoma patients have myasthenia gravis.

• Accuracy of diagnosis and staging based on history and physical examination, laboratory and imaging studies. Tissue diagnosis by FNA or core biopsy is required before definitive treatment.

• Stage, completeness of surgical resection, and pathology are the most important prognostic factors. The Masaoka staging system is widely used.

• Thymoma usually present with an indolent behavior. Local and regional extension are the main modes of disease progression. Distant metastasis is rarely observed in thymoma, but can occur in thymic carcinoma.

• Treatment of thymoma depends on the resectability of the disease and surgery is the mainstay of therapy. Completeness of resection is prognostically significant.

• Adjuvant radiation therapy is recommended for stage II and III, as well as for residual disease (including positive margins). Radiation therapy is not necessary after complete resection for stage I cases.

• Neoadjuvant chemotherapy is indicated in unresectable cases. Chemotherapy followed by radiotherapy is recommended if surgical resection is not feasible.

• Long-term overall survival rates are 95%, 90%, 70%, and 23% for WHO type A, AB, B, and C diseases after treatment.