Subclinical myasthenia gravis in thymomas.

Area of Science:

• Neurology
• Immunology
• Thoracic Surgery

Background:

• A subset of thymoma patients without prior myasthenia gravis (MG) exhibit positive anti-acetylcholine receptor (AChR) antibodies.
• These subclinical MG cases may be underdiagnosed due to inconsistent antibody testing in asymptomatic individuals.
• The prevalence and long-term outcomes of subclinical MG in thymoma patients remain largely undescribed.

Purpose of the Study:

• To determine the prevalence of subclinical myasthenia gravis (MG) in patients with thymoma.
• To investigate the long-term outcomes of subclinical MG in this patient population.
• To assess the diagnostic value of anti-acetylcholine receptor (AChR) antibody testing prior to thymectomy.

Main Methods:

• Retrospective analysis of 398 patients undergoing robotic-assisted thoracoscopic surgery for thymic diseases.
• Inclusion criteria: thymoma, thymectomy at MUMC+, minimum one-year follow-up, age >18.
• Exclusion criteria: thymic carcinomas, refusal, loss to follow-up.

Main Results:

• 102 thymoma patients were included; 87 were tested for anti-AChR antibodies pre-thymectomy.
• Seven subclinical MG patients were identified pre-thymectomy, with an additional four discovered post-thymectomy, totaling 11 (10.8% prevalence).
• 91% of subclinical MG patients developed clinical MG within six years; two died from myasthenic crisis.

Conclusions:

• Subclinical myasthenia gravis (MG) has a prevalence of 10.8% in thymoma patients.
• A significant majority (91%) of subclinical MG patients develop clinical MG within six years post-thymectomy.
• Routine anti-acetylcholine receptor (AChR) antibody testing is recommended for all thymoma patients before thymectomy.