Non-cancerous diseases of the thymus

Hyperplasia
Hyperplasia is characterized by the formation of lymphatic follicles, which are absent in normal thymic tissue. Hyperplasia is typical for patients with autoimmune diseases (myasthenia gravis, lupus erythematodes and rheumatoid arthritis).

Dysgenesis
Dysgenesis, or impaired thymic development, is part of the primary immunodeficiency states. Especially in syndromes like DiGeorge syndrome and Nezelof, when cellular immunity is impaired. In these diseases, the thymus is replaced by a fibrous cord, or is completely absent.

Regressive changes

 * Physiological involution (lipomatous atrophy) begins during puberty, when lipocytes begin to accumulate in the thymus. During the involution, the number of thymocytes decreases and at the same time the calcification of Hassl's bodies occurs. The thymus does not completely disappear during adolescence, the residue can be also found during adulthood.
 *  Acute involution of the thymus is a disease caused by adrenal steroids. It is caused by stress in the body, such as malignant tumours, infections, starvation and cachexia. Thymocyte fragmentation and aggregation occurs, as well as macrophage proliferation and cystic transformation of Hassal's bodies.

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