Myasthenia gravis: a long term follow-up study of Swedish patients with specific reference to thymic histology.
BACKGROUND
Myasthenia gravis (MG) is an autoimmune disorder of neuromuscular transmission. The majority of patients show abnormal thymic histology.


METHODS
The study was performed at the Myasthenia Gravis Centre, Karolinska University Hospital, and at the Immunological Research Laboratory, Centre for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.


METHODS
Information was collected retrospectively from 1956 and prospectively from 1975 on clinical data, concomitant diseases, concentration of serum acetylcholine receptor antibodies (AChR-abs), immunosuppressive treatment (IS) and response to it, in 537 patients of whom 326 were thymectomised. Follow-up time was 1.5-50 years.


RESULTS
Age at onset of MG increased from a median age of 24 years before 1975 to a median age of 61 years after 2000. Thymoma was found in 65, hyperplasia (HPL) in 185 and a normal thymus in 76 patients. The trans-sternal surgical approach for thymectomy was used in 255 patients (78%). In five patients with thymoma, MG appeared after thymectomy. Of 537 patients, 466 (87%) had circulating AChR-abs. IS was given to 300 (56%) patients, mostly those with thymoma (85%). In total, 441 patients (82%) showed an improvement. One-third of patients with HPL, a quarter of those with thymoma, one-fifth of those with a normal thymus and one-seventh of those not operated on went into remission.


CONCLUSIONS
The prognosis for the majority of patients with MG is favourable, irrespective of thymic histology. The cause may be the use of immunomodulating therapy.
Tsinzerling
Natalie
N
Department of Medicine, Immunological Research Laboratory, Centre for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.
Lefvert
Ann-Kari
AK
Matell
Georg
G
Pirskanen-Matell
Ritva
R
D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies; D002278:Carcinoma in Situ / Q000453:epidemiology; D015984:Causality; D015897:Comorbidity; D004700:Endocrine System Diseases / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007165:Immunosuppression Therapy; D015994:Incidence; D008206:Lymphatic Diseases / Q000453:epidemiology* / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000453:epidemiology* / Q000276:immunology / Q000628:therapy; D011159:Population Surveillance; D011446:Prospective Studies; D011950:Receptors, Cholinergic / Q000276:immunology; D012189:Retrospective Studies; D015996:Survival Rate; D013548:Sweden / Q000453:epidemiology; D013934:Thymectomy; D013950:Thymus Gland / Q000473:pathology* / Q000601:surgery; D013953:Thymus Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000601:surgery; D016896:Treatment Outcome; D002583:Uterine Cervical Neoplasms / Q000453:epidemiology
D000906:Antibodies; D011950:Receptors, Cholinergic