Research article

The role of a pseudocapsula in thymic epithelial tumors: outcome and correlation with established prognostic parameters. Results of a 20-year single centre retrospective analysis

Sebastian Dango¹ , Bernward Passlick¹ , Ulf Thiemann² , Gian Kayser² and Christian Stremmel¹

¹  Clinic for Thoracic Surgery, Hugstetter Str. 55, University Hospital Freiburg, Albert-Ludwig-University, 79106 Freiburg, Germany

²  Pathological Institut of University Hospital Freiburg, Breisacherstr. 115, Albert-Ludwig University, 79106 Freiburg, Germany

author email corresponding author email

Journal of Cardiothoracic Surgery 2009, 4:33doi:10.1186/1749-8090-4-33

Published:	15 July 2009

Abstract

Background

Treatment of thymoma is often based on observation of only a few patients. Surgical resection is considered to be the most important step. Role of a pseudocapsula for surgery, its clinical significance and outcome compared with established prognostic parameters is discussed which has not been reported so far.

Methods

84 patients with thymoma underwent resection and analysis was carried out for clinical features, prognostic factors and long-term survival.

Results

Fifteen patients were classified in WHO subgroup A, 21 in AB, 29 in B and 19 patients in C. Forty two patients were classified in Masaoka stage I, 19 stage II, 9 stage III and 14 stage IV. Encapsulated thymoma was seen in 40, incomplete or missing capsula in 44 patients. In 71 complete resections, local recurrence was 5%. 5-year survival was 88.1%. Thymomas with pseudocapsula showed a significant better survival (94.9% vs. 61.1%, respectively) (p = 0.001) and was correlated with the absence of nodal or distant metastasis (p = 0.04 and 0.001, respectively). Presence of pseudocapsula as well as the Masaoka and WHO classification, and R-status were of prognostic significance. R-status and Masaoka stage appeared to be of independent prognostic significance in multivariate analysis.

Conclusion

Intraoperative presence of an encapsulated tumor is a good technical marker for the surgeon to evaluate resectability and estimate prognosis. Although the presence of a capsula is of strong significance in the univariate analysis, it failed in the multivariate analysis due to its correlation with clinical Masaoka stage. Masaoka stage has a stronger relevance than WHO classification to determinate long-term outcome.