Thymoma: current diagnosis and treatment

Abstract

Objective To review the presentation, diagnosis, staging and treatment of thymoma. Data sources Data were obtained from papers on thymoma published in English within the last 30 years. No formal systematic review was conducted, but an effort was made to be comprehensive. Study selection Studies were selected if they contained data relevant to the topic addressed in the particular section. In particular, standards adopted by the International Thymic Malignancies Interest Group through a formal process of achieving worldwide consensus are featured. Because of the limited length of this article, we have frequently referenced recent reviews that contain a comprehensive amalgamation of literature rather than the actual source papers. Results Thymomas are rare malignant tumors. They account for about half (47%) of anterior mediastinal tumors. About one third of these are associated with myasthenia gravis. Computed tomography with intravenous contrast is the standard diagnostic modality. Thymomas appear as round or oval masses in early stages but irregular shapes with calcifications occurring in later stages. They can invade surrounding structures including mediastinal fat, pleura, major blood vessels and nerves. Fine needle aspiration, core needle biopsy or open biopsy is used to obtain tissue diagnosis. Masaoka-Koga classification is currently used to stage thymomas. All thymomas should be considered for resection due to their malignant potential. A complete resection is a major prognostic factor and every effort should be made to achieve this even if this means resection and reconstruction of a major thoracic structure. Median sternotomy is the standard approach for thymoma resection. A number of minimally invasive techniques are used in selective centers. While stage I and II tumors undergo primary surgery, preoperative chemotherapy appears to increase the chances of complete resection for stage III and IVa tumors. Postoperative radiation could be considered for patients with residual disease. Excellent 5 and 10-year survival rates are noted for completely resected early stage thymomas. Conclusions Thymic malignancies are rare tumors. Standards have recently been achieved to allow better communication and promote collaborative research. Surgical resection is the mainstay of treatment, but a multimodality approach is useful for many patients.