[Thymoma and thymic carcinoma--review of literature and clinical characteristics based on the Polish Paediatric Solid Tumours Study Group experience].

Thymomas and thymic carcinomas are rare neoplasms derived from the epithelial tissue of thymus, very infrequently developing in young adults and children. The estimation of thymomas' invasiveness has been the matter of discussion for many years reflected by numerous clinical and histological classifications. In 1999 the WHO classification was created, joining all the most important issues present in previously used systems. It is believed that histological structure is the most important prognostic factor in thymic carcinomas while in less aggressive types of thymomas the clinical stages influence the outcome. Staging of thymomas is most commonly based on the Masoka classification. Independent evaluation of the stage and histological aggressiveness are necessary to predict the clinical course and outcome in thymomas. Thus the term 'malignant thymoma' has been replaced by 'invasive thymoma' in clinical practice. The treatment strategy depends on the clinical stages of thymoma. Complete resection of the tumour is the treatment of choice with supplementing radiotherapy in more advanced clinical stages. Chemotherapy in invasive thymomas has been reported to play an increasingly important role as induction, supplementing and palliative therapy. It has been proved that combined treatment improves the outcome in invasive thymomas, especially in thymic carcinomas. This paper reviews the literature data concerning the histology, clinical issues and treatment of thymomas and thymic carcinomas. The clinical data on nine children with thymic carcinomas treated between 1992 and 2006 in the Polish oncological and surgical centres were also analysed and presented. Based on multicentre data we were able to conclude the following: 1. Thymic carcinomas in children are very rare and that is why early diagnosis is often difficult. 2. At diagnosis most cases are already inoperable, which results in poorer prognosis. 3. Complex adjuvant chemo- and radiotherapy in childhood thymic carcinomas seem to prolong overall survival. 4. Further detailed analysis in all the cases of thymic carcinomas in children is recommended in order to estimate the optimal strategy of treatment.