The Pathological Studies Of Thymomas And Clinical Diagnosis And Treatments Of Myasthenia Gravis With Thymomas

Objective To study the WHO classification and traditional classification of thymomas and evaluate their clinical values.Materials Ninety-five cases of thymomas were studied by traditional classification and the classification proposed by the World Health Organization (WHO). The relationships between the subtypes and myathenia gravis, invasiveness and prognosis were analyzed.Results In traditional classification, there were 19 cases of predominantly epithelial thymoma, 42 cases of predominantly lymphocytic thymoma, 22 cases of mixed type, 7 cases of spindle cell type and 5 cases of thymic carcinoma. The spindle cell type was less invasive and accompanied with less MG. The predominantly epithelial thymomas were more invasive than predominantly lymphocytic thymomas (P<0.01), with 58% invasive to surrounding important organs. Eighty-two percent of mixed type was accompanied with MG and there was not difference between mixed type and predominantly epithelial type and predominantly lymphocytic type (P>0.05). In WHO classification, there were 7 cases of type A, 16 cases of type AB, 33 cases of type B1, 24 cases of type B2, 10 cases of type B3 and 5 cases of type C. Myasthenia gravis was associated in 16.7%, 50%, 71.4%, 91.7%, 66.7% and 0% in patients with type A, AB, Bl, B2, B3 and C thymomas, respectively. Invasive tumors were seen in 16.7% 31.3% 31.4% 70.8%, 100% and 100% of type A, AB, Bl, B2, B3 and C thymomas, respectively. The survival rate at five years of A and AB types was 91.7%, B types 73.1% (Bl 84.6%, B2 62.5%, B3 60%) and C type 33.3% respectively. The survival rates were significantly higher for patients with A and AB types of thymomas than patients with B and C types of thymomas (P0.05 and P0.01).Conclusion The B types of thymomas in WHO classification were more invasive and associated with myasthenia gravis and had poor prognosis, whereas the A type was less associated with myasthenia gravis and had better prognosis. The WHO classification of thymomas was closely related to accompany with myasthenia gravis and reflected the clinical features and the functions of thymic epithelial tumors.