Thymic histology in myasthenia gravis.

ABSTRACT

Histological features of resected thymuses of 18 patients with myasthenia gravis were evaluated. Thymoma were seen in 16.6% of the patients. In the non-thymomatous group, thymic hyperplasia with follicle formation was seen in 33.3%, involuted thymus with occasional lymphoid follicle formation in 11.1%, thymitis with B cell infiltration in 16.6%, involuted thymus in 11.1% and normal thymus in 11.1% of patients. Immuno-histological staining for B and T lymphocytes delineated the group labelled as thymitis with B cell infiltration. Mast cell and eosinophils were frequently seen in thymuses with thymic hyperplasia with follicle formation and thymitis with B cell infiltration. Thymic hyperplasia with follicle formation was more frequent in young patients and these patients had better prognosis.