Editing Thymus (section)

====Thymomas====
Tumours originating from the thymic epithelial cells are called [[thymomas]].<ref name="Robbins9th" /> They most often occur in adults older than 40.<ref name="Robbins9th" /> Tumours are generally detected when they cause symptoms, such as a [[neck mass]] or affecting nearby structures such as the [[superior vena cava]];<ref name=":2" /> detected because of screening in patients with myasthenia gravis, which has a strong association with thymomas and hyperplasia;<ref name="Robbins9th" /> and detected as an [[Incidental medical findings|incidental finding]] on imaging such as [[chest X-ray]]s.<ref name=":2" /> [[Hyperplasia]] and tumours originating from the thymus are associated with other autoimmune diseases – such as [[hypogammaglobulinemia]], [[Graves disease]], [[pure red cell aplasia]], [[pernicious anaemia]] and [[dermatomyositis]], likely because of defects in negative selection in proliferating T cells.<ref name="Robbins9th" />{{sfn|Harrison's|2015|pp=2759}}

Thymomas can be benign; benign but by virtue of expansion, invading beyond the capsule of the thymus ("invasive thymoma"), or malignant (a [[carcinoma]]).<ref name="Robbins9th" /> This classification is based on the appearance of the cells.<ref name="Robbins9th" /> A [[World Health Organization|WHO]] classification also exists but is not used as part of standard clinical practice.<ref name="Robbins9th" /> Benign tumours confined to the thymus are most common; followed by locally invasive tumours, and then by carcinomas.<ref name="Robbins9th" /> There is variation in reporting, with some sources reporting malignant tumours as more common.{{sfn|Harrison's|2015|pp=2759}} Invasive tumours, although not technically malignant, can still spread ({{wt|en|metastasise}}) to other areas of the body.<ref name="Robbins9th" /> Even though thymomas occur of epithelial cells, they can also contain thymocytes.<ref name="Robbins9th" /> Treatment of thymomas often requires surgery to remove the entire thymus.{{sfn|Harrison's|2015|pp=2759}} This may also result in temporary remission of any associated autoimmune conditions.{{sfn|Harrison's|2015|pp=2759}}