Thymoma

Excerpt

Thymomas and thymic carcinomas originate from the epithelial cells of the thymus within the anterior mediastinum. The thymus is an encapsulated bilobed gland. Each lobe of the thymus has a superior and inferior horn and extends laterally to each respective phrenic nerve. The thymus is supplied by branches off of the internal mammary, inferior thyroid, and pericardiophrenic arteries. It is drained by tributaries from the innominate vein or directly into the superior vena cava (SVC). The thymus is vital in the development of the adaptive immune system and commonly involutes after puberty into fibrofatty tissue. There has been a strong association between myasthenia gravis and thymomas that was found incidentally in 1939 by Alfred Blalock. The presence of histologic heterogeneity is common among thymomas, and as a result, benign and malignant thymomas cannot simply be differentiated based on history; however, malignant thymomas are much more invasive compared to their benign counterpart. The 15-year survival rate is 12.5% in patients with invasive thymomas and 47% in patients with noninvasive thymomas. Deaths related to thymomas usually occur from cardiac tamponade or other cardiorespiratory complications.