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Thymus histology and concomitant autoimmune diseases in J apanese patients with muscle‐specific receptor tyrosine kinase‐antibody‐positive myasthenia gravis
Author(s) -
Nakata R.,
Motomura M.,
Masuda T.,
Shiraishi H.,
Tokuda M.,
Fukuda T.,
Ando T.,
Yoshimura T.,
Tsujihata M.,
Kawakami A.
Publication year - 2013
Publication title -
european journal of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 124
eISSN - 1468-1331
pISSN - 1351-5101
DOI - 10.1111/ene.12169
Subject(s) - myasthenia gravis , medicine , thymoma , autoantibody , concomitant , autoimmune disease , histology , gastroenterology , antibody , immunology , pathology , endocrinology
Background and purpose The differences in the characteristics of thymus histology, coexisting autoimmune diseases and related autoantibodies between anti‐muscle‐specific receptor tyrosine kinase ( M u SK )‐antibody ( A b)‐positive myasthenia gravis ( MG ) patients, and anti‐acetylcholine receptor ( AC h R )‐ A b‐positive MG patients are not clearly defined. Methods The types of thymus histology, coexisting autoimmune diseases and associated Abs in 83 M u SK ‐ A b‐positive patients nationwide were investigated and were compared with those in AC h R ‐ A b‐positive patients followed at our institute ( n = 83). As for the autoantibodies associated with thymoma, titin Abs were measured. Results Thymoma was not present in any of the M u SK ‐ A b‐positive patients but presented in 21 patients (25.3%) amongst the AC h R ‐ A b‐positive patients. Titin Abs were absent in M u SK ‐ A b‐positive patients but positive in 25 (30.1%) of the AC h R ‐ A b‐positive patients. Concomitant autoimmune diseases were present in eight M u SK ‐ A b‐positive patients (9.6%) amongst whom H ashimoto's thyroiditis and rheumatoid arthritis predominated, whereas 22 AC h R ‐ A b‐positive patients (26.5%) had one or more concomitant autoimmune diseases of which G raves' disease predominated. Conclusions Differences in frequency of thymoma and thymic hyperplasia, coexisting autoimmune diseases and autoantibody positivity between M u SK ‐ A b‐positive and AC h R ‐ A b‐positive MG were indicated, suggesting that, in contrast with AC h R ‐ A b‐positive MG , thymus does not seem to be involved in the pathogenic mechanisms of M u SK ‐ A b‐positive MG .