Myasthenia gravis with thymoma

Progress in the pathogenesis, diagnosis, and treatment of thymomatous myasthenia gravis (MG) has been made in the past several decades. These advances have occurred along diverse lines of immunology, molecular genetics, and tumor cytopathology. The most widely used classification for thymoma closely correlates with tumor biology, prognosis, and the likelihood of association with MG. There is a sensitive immunoassay for the detection of striational autoantibodies, which are closely related to the presence of thymoma, although their precise origin is still debated. Chest computed tomography (CT) can delineate a thymoma with extraordinary accuracy and sensitivity. The goal of treatment is complete removal of the tumor and remission or sustained improvement of MG. This is usually achievable with trans-sternal maximal thymectomy and chronic immunosuppressant medication. In this article, we consider aspects of the historical background, pathogenesis, diagnosis, and treatment of thymomatous MG.

Historical background.

There was no mention of thymic abnormalities in the classic descriptions of myasthenia patients by Wilks, ^[1] Erb, ^[2] Goldflam, ^[3] and Jolly, ^[4] or among the autopsies reported by Campbell and Bramwell at the turn of the century ^[5] until 1901 when Laquer and Weigert ^[6,7] described a patient with myasthenia and a thymic tumor. Later, Bell, ^[8] Blalock, ^[9,10] and others found that the thymus gland in myasthenia was enlarged or the site of a tumor in the majority of patients at surgery or autopsy. Thymectomy, with the intention to resect the gland totally became standard treatment. ^[11-15]

The estimated overall frequeny of thymoma in MG varies from 15 to 30%. ^[16-22] It is more common with increasing age, with an estimated frequency of 3% for age 20 years or younger, 12% for ages 21 to 45, and 35% for age 46 years and older. ^[23] Although detection of thymoma most often follows the clinical diagnosis of MG, …