A quantitative study was performed regarding the occurrence and density of thymic lymphoid follicles in 125 cases of biopsied thymus in various diseases and 71 cases of autopsied subjects from accidental death.
1. The incidence of thymic lymphoid follicles in myasthenia gravis was 83.8% and strikingly high in comparison with other diseases. Furthermore, in cases showing severe clinical symptom of myasthenia gravis, the incidence goes up to 100%.
In hyperthyroidism the incidence of lymphoid follicles was high (66.7%), next to myasthenia gravis. The incidence in autoimmune disease excluding myasthenia gravis and hyperthyroidism was 39.1%. Follicular incidence in control thymus was very low (16.9%) as compared with Middleton's report.
Lymphoid follicles were found very frequently in the thymic tissue of cases with thymoma associated with myasthenia gravis and Hashimoto thyroiditis, whereas no lymphoid follicles were observed in cases without such complications. The frequency of occurrence of thymic lymphoid follicles in women was similer to that in men.
2. Thymic lymphoid follicles occurrec in a high frequency among aged people with myasthenia gravis and autoimmune disease, while occurrence of lymphoid follicles was restricted in the first and second decades in non-autoimmune disease and accidental death.
3, The number of the thymic lymphoid follicles per lobule in myasthenia gravis was higher that in other diseases. There was a parallelism between the severity of muscle weakness and density of lymphoid follicles per lobule, although the correlative coefficient was not high.
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