The thymus is associated with various diseases. But which diseases are associated with the thymus? These include thymoma, the autoimmune disease myasthenia gravis, Di-George syndrome, and multiple sclerosis. In the following, we introduce the diseases in more detail.
Thymoma: tumor on the thymus.
Rarely, a tumor occurs on the thymus, called a thymoma. Most thymomas grow very slowly; only malignant thymoma (thymic carcinoma) grows rapidly. When the tumor grows larger, it can increasingly press on neighboring structures such as the trachea or bronchi.
Autoimmune diseases such as myasthenia gravis often occur in connection with thymomas. The thymus must then be surgically removed (thymectomy), which in children can have an impact on the immune system, which is not yet fully developed.
Myasthenia gravis
This autoimmune disease weakens the transversely striated muscles. The eyelids and external eye muscles (occurrence of double vision) and the chewing and pharyngeal muscles (difficulty chewing and swallowing) are particularly affected. Typically, the symptoms worsen with exertion. In a myasthenic crisis, the respiratory muscles may also be affected and shortness of breath may occur.
The thymus is thought to play an important role in the development of myasthenia gravis because it is enlarged in many affected individuals. In some cases, therefore, surgical removal of the thymus has a positive effect on the course of the disease. A thymoma can also cause myasthenia gravis by producing those autoantibodies that attack its own body.
Di George syndrome
In this congenital disease, there is a defect on chromosome 22 or 10. In addition to heart defects, for example, children with this disease have either a weakly developed thymus (thymic hypoplasia) or no thymus at all (thymic aplasia). The T-cells cannot mature, therefore the immune system is weakened. Depending on the severity of the syndrome, the children are somewhat more susceptible to infectious diseases or are constantly at their mercy.
In such cases, attempts are made to transfer mature T cells from a suitable donor (for example, a sibling). In America, a new form of therapy is being tested in which thymus tissue is transplanted from another person.
Multiple sclerosis
Multiple sclerosis (MS) is a serious autoimmune disease in which immune cells attack and destroy healthy nerve tissue. It is due to a defect in the immune defense system, which is supposed to destroy only cells foreign to the body. So-called regulatory T cells normally ensure that our immune system recognizes and spares the body’s own cells.
In MS patients, the thymus is apparently unable to produce enough new regulatory T cells. This deficiency is compensated for by the proliferation of older T cells, but these are no longer as effective and cannot prevent the attack on the body’s own nerve cells.
