Analysis of prognostic factors and clinicopathological staging of thymoma The prognostic value of four clinical variables (age and sex of patients, association with myasthenia gravis, and clinical stage) and histological type was analyzed in 83 consecutive patients with thymoma, histologically classified as cortical, medullary, and mixed. Age, sex, and association with myasthenia gravis did not prove to represent significant prognostic factors; clinical stage and histological type, on the contrary, had a highly significant prognostic value (p less than 0.001). A model of clinicopathological staging, based on both clinical stage and histological type, in which three major prognostic groups are considered is proposed. The degree of significance of this model is higher (p less than 0.0001) than that of clinical stage and histological type considered individually; its validity is further supported by the results of multivariate analysis according to the Cox regression model (p = 0.0001). We think it represents a prognostically valuable approach to the problem of management of thymoma. 