Thymomas are rare mediastinal tumors that have heterogeneous microscopic morphology and uncertain outcome.
Aim: The aim of the study was to evaluate the practical usefulness of WHO classification by correlation of histological subtype of thymoma with staging, symptoms and epidemiology.
Material and methods: 87 cases of thymomas was reclassified according to the WHO Histologic classification and Masaoka staging system. Clinical symptoms, age and sex of the patient were taken into consideration in each case.
Results: The histological subtypes was diagnosed in order of frequency: AB (n = 21; 24%), B2 (n = 19; 22%), B1 (n = 14; 16%), A (n = 6; 7%), C (n = 4; 5%), B3 (n = 3; 3%). Combined types was observed in 17 (20%) cases. Tendency to invasion increased as follows: A < AB < B1 < B2 < B3 < C. The median value of patients' age was: type A--67,5 years, type AB--62 yrs., type B1--48 yrs., type B2--52 yrs., type B3--32 yrs. and type C (thymic carcinoma)--49,5 yrs. No correlation was found between histological type and sex of patient. The most often clinical symptom--myasthenia, accompanied predominantly B2 thymomas.
Conclusions: The WHO classification is useful in routine pathologic examination of thymomas, because it enables to distinguish histological subtypes with different clinical representation.