[Thymic lymphoid hyperplasia of myasthenia gravis patients: correlation with clinical features and efficacy of thymectomy].

Thirty nine thymus tissues from myasthenia gravis patients without thymoma who underwent extended thymectomy were evaluated on thymic lymphoid hyperplasia with special emphasis on clinical features and the efficacy of thymectomy. Of 39 patients, 31 were women, but 3 of 7 patients without thymic lymphoid hyperplasia were men. The hyperplastic index of the thymus correlated largely with serum anti-Ach-R antibody titers before surgery. Age, myasthenic type and preoperative duration of the symptoms were almost unrelated to the hyperplastic change in the thymus. The effect of thymectomy was more remarkable in the patients with the hyperplastic thymus than that in them without it, who obtained still no remission after surgery, although the remission rate of them with it reached to 25%. Of 7 patients without the hyperplastic thymus, 4 had no detectable antibody to acetylcholine receptor, whereas in 32 patients with it only 2 were seronegative. This negative immunological factor might make adverse response to thymectomy. Although unfavorable response to thymectomy were observed in the patients without the hyperplastic thymus, most of them were significantly improved through a supplementary treatment with steroid after surgery. Thymectomy was a favorable treatment for myasthenia gravis patients with thymic lymphoid hyperplasia, whereas in them without it the result of thymectomy was unsatisfactory.