title: Comparison of the histological and immunohistochemical features of the thymus in young- and elderly-onset myasthenia gravis without thymoma.
abstract: We performed histological and immunohistochemical analyses of the removed thymuses from 20 elderly (onset age > 60 years) and 23 young (onset age < 40 years) patients with myasthenia gravis (MG) who tested positive for serum anti-acetylcholine receptor (AChR) antibodies, but who did not have associated thymoma. In the elderly group, nine (45%) patients had accumulations of lymphocytes, indicating an atrophied thymus with loss of the basic structure. The elderly MG patients with atrophied thymic tissues had higher titres of anti-AChR antibody (59.6+/-81.0 nmol/L) than those with adipose infiltration of the thymus alone (20.1+/-20.9 nmol/L). In immunohistochemical studies using image analysis, both young patients and elderly patients with atrophied thymic tissues were found to have significantly higher levels of CD20 than age-matched controls (p < 0.005). Atrophied thymic tissues, often seen immunohistochemically in young MG patients, may also be found in elderly patients, particularly in those with high titres of the anti-AChR antibody, even though adipose infiltration is marked in these patients.
authors.affiliation: Third Department of Medicine, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Ishii
authors.forename: Masayuki
authors.initials: M
authors.lastname: Matsuda
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hanyuda
authors.forename: Masanobu
authors.initials: M
authors.lastname: Momose
authors.forename: Jun
authors.initials: J
authors.lastname: Nakayama
authors.forename: Takashi
authors.initials: T
authors.lastname: Ehara
authors.forename: Shu-Ichi
authors.initials: S
authors.lastname: Ikeda
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D001284:Atrophy; D001323:Autoantibodies / Q000097:blood; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000276:immunology; D007150:Immunohistochemistry; D008214:Lymphocytes / Q000473:pathology; D008297:Male; D016555:Matched-Pair Analysis; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000097:blood / Q000150:complications / Q000276:immunology / Q000473:pathology*; D011950:Receptors, Cholinergic / Q000276:immunology*; D018709:Statistics, Nonparametric; D013945:Thymoma / Q000150:complications*; D013950:Thymus Gland / Q000276:immunology / Q000473:pathology*; D013953:Thymus Neoplasms / Q000150:complications*
chemical_list: D001323:Autoantibodies; D011950:Receptors, Cholinergic