Clinical examination of thymus and neck

The thymus is enlarged in a condition known as myasthenia gravis.   In this condition the motor and plates are affected so that acetylcholine produced at these and plates to facilitate neuromuscular transmission of impulses which affect muscular contraction, is broken down by high levels of acetylcholinesterase.   But the basic problem is that the acetylcholine proteins (receptors) to which acetylcholine molecules are attached are removed by antibodies against them produced by sensitized T lymphocytes (autoimmune antibodies). This then leads to weakness of muscles.   The  thymus  becomes very enlarged in this condition.   Histology of thymus shows thymic hyperplasia. Thymectomy is practiced as a surgical therapeutic procedure. Myasthenia gravis is an autoimmune disease.

Thymomas may arise as neoplastic transformation of epitheliocytes of the thymus.

In DiGeorge syndrome there is hypoplasia of thymus due to lack of development of third and fourth pharyngeal pouches. It therefore affects thymus and parathyroid glands. It causes congenital immune deficiency syndrome affecting only cellular immunity and it genetic defect is mapped to 22q11.

Anatomy       Thymus page

  • Thymus hypoplasia

  • Thymus hyperplasia

  • Benign thymoma

  • Malignant thymoma




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