Rare clinical case of thymoma type A: clinical characteristics and results of stereotactic irradiation of multiple liver metastases

The article presents a rare clinical case of a 72-year-old patient with a clinical diagnosis: Thymoma, type A, metastatic brain, lung, and liver damage. The incidence of thymoma varies in the range from 0.2 to 1.5% of all malignancies. Morphological classification, revised by WHO in 2015, distinguishes subtypes of thymoma depending on the histological structure (A, atypical A, AB, B1, B2, B3). This classification takes into account the shape of the tumor cells and the amount of the lymphocytic component. The Masaoka classification (1981), as well as the TNM classification, are widely used for thymoma staging by the degree of invasion into surrounding tissues. Thymomas are usually indolent tumors with a relatively favorable prognosis. They rarely (3 - 5%) metastasize beyond the chest. According to the literature, subtype A is the most favorable variant of thymoma, with a favorable prognosis and overall survival of more than 15 years. This article presents a rare clinical case of histologically confirmed type A thymoma with an aggressive course characterized by multiple distant metastasis. The article also describes the result of stereotactic irradiation of thymoma metastases in the liver.