RECURRENT THYMOMA - EVIDENCE FOR HISTOLOGICAL PROGRESSION

The clinicopathological features of nine cases of recurrent thymomas h ave been studied, At presentation, all cases were histologically class ified as thymomas with cortical differentiation, including predominant ly cortical thymoma, cortical thymoma and well-differentiated thymic c arcinoma, In five cases the morphological features of the recurrence(s ) were suggestive of a histological progression of the tumour from pre dominantly cortical thymoma to cortical thymoma and/or well-differenti ated thymic carcinoma, usually associated with a more advanced clinica l stage, the latter indicating a clinical progression, These findings suggest that all types of thymoma with cortical differentiation are hi stologically and histogenetically related neoplasms, associated with a more aggressive clinical behaviour and a significant risk of recurren ce, The overall outcome of patients with recurrent thymoma in this ser ies was poor, since six patients (66.6%) died due to the disease, 2-14 years after the first diagnosis, The clinical implication of our find ings is that thymomas with cortical differentiation always need carefu l follow-up, even in those cases which are not obviously invasive at o nset.