[Clinical pathological study of resected thymus from 104 myasthenia gravis patients]

One hundred and four thymuses from patients with myasthenia gravis were reviewed for clinical pathological manifestations. 6 cases were examined by immunohistochemical techniques with CK, EMA, CEA, UCHT1, T4, T8, L26, S-100 and electronmicroscopy. 73 cases had long term follow-up after thymectomy. Microscopically, there was lymphocytic hyperplasia associated with formation of germinal centers and branching proliferation of capillaries, which were characteristic. Electronmicroscopically there were abundant cytoplasmic projections of lymphocytes. Interdigitating pattern of the projections were frequently seen between the lymphocytes and crevice-like patterns were formed between the endothelial cells of capillaries. Immunohistochemically, the thymus had both proliferation of T cells (UCHT1, T4) and B cell reaction (L26) as well as CK and S-100 positive cell expression. It is suggested that the prognosis of myasthenia gravis after resection of thymus is related to clinical type, age and pathological changes. 95.1% of adult type I or II cases which were associated with hyperplasia of lymphoid tissue of the thymus, but not thymomas, improved after thymectomy and had better prognosis than others.