A Serological Test for Thymoma in Patients with Myasthenia Gravis

Ten to fifteen percent of patients with myasthenia gavis (MG) have an underlying thymoma. Such patients do less well and it may be important to detect them early. Conventional tests for thymoma such as immunofluorescent demonstration of skeletal muscle antibodies and CT scanning of the anterior mediastinum may give false positive and false negative results. We have attempted to validate a report that antibodies to a citric acid extract (CAE) of muscle, demonstrated by an indirect haemagglutination technique, are specific for thymoma. We studied four groups of subjectsnormal controls, patients with other neuromuscular disease (OND), MG patients with known thymic histology, and MG patients with unknown thymic histology. CAE antibodies were not detected in any normal controls or patients with OND. In the group with known thymic histology they were found in all those with thymoma and none of those with other histology. They