Measurement of antiacetylcholine receptor antibody in patients with thymoma without myasthenia gravis complications.

OBJECTIVE

Some patients with thymoma reported to show higher antiacetylcholine receptor antibody titers without the preoperative occurrence of myasthenia gravis and some have suffered postoperative complications of myasthenia gravis despite being negative for antiacetylcholine receptor antibody preoperatively. We evaluated changes in antiacetylcholine receptor antibody titers and the occurrence of myasthenia gravis in thymoma patients.

METHODS

Subjects were 31 of 44 patients with thymoma undergoing thymothymectomy at Tokyo Women's Medical University Hospital between 1987 to 1999 in whom antiacetylcholine receptor antibody titers were measured preoperatively. We studied postoperative changes in antiacetylcholine receptor antibody titers and the presence or absence of myasthenia gravis.

RESULTS

Eight patients were positive for antiacetylcholine receptor antibody preoperatively, suggesting the presence of subclinical myasthenia gravis. Neither postoperative changes in antiacetylcholine receptor antibody titers nor the occurrence of myasthenia gravis was observed in these 8 patients. Recurrent thymoma and rapid elevation of antiacetylcholine receptor antibody titers were observed postoperatively in 1 patient negative for antiacetylcholine receptor antibody preoperatively, resulting in manifestation of myasthenia gravis symptoms.

CONCLUSION

We found no correlation between preoperative titers and myasthenia gravis symptoms. Rapid titer elevation indicates the occurrence of myasthenia gravis symptoms or the recurrence of thymoma.