Protein expression status of p53 and epidermal growth factor receptor in thymoma

Diagnostic Roles of Immunohistochemistry in Thymic Tumors: Differentiation between Thymic Carcinoma and Thymoma

Background: The present study aims to evaluate the diagnostic roles of various immunohistochemical (IHC) markers in thymic tumors, including thymic carcinoma (TC) and thymoma (TM). Methods: Eligible studies were obtained by searching the PubMed databases and screening the searched articles. Thirty-eight articles were used in the present meta-analysis and included 636 TCs and 1861 TMs. Besides, for IHC markers with statistical significance, a diagnostic test accuracy review was performed. Results: The comparison of various IHC expressions between TC and TM was performed for 32 IHC markers. Among these IHC markers, there were significant differences between TC and TM for beta-5t, B-cell lymphoma 2 (Bcl-2), calretinin, CD1a, CD5, carcinoembryonic antigen (CEA), cytokeratin19 (CK19), CD117, glucose transporter 1 (Glut-1), insulin-like growth factor 1 receptor (IGF-1R), mesothelin, MOC31, mucin1 (MUC1), p21, and terminal deoxynucleotidyl transferase (TdT). Markers with higher expressions in TCs were Bcl-2, calretinin, CD5, CEA, CD117, Glut-1, IGF-1R, mesothelin, MOC31, MUC1, and p21. Among these markers, there were no significant differences between TC and TM type B3 in immunohistochemistries for Bcl-2 and CK19. On the other hand, β-catenin and CD205 showed a considerable difference in IHC expressions between TC and TM type B3, but not between TC and overall TM. In diagnostic test accuracy review, MUC1 and beta-5t were the most useful markers for TC and TM, respectively. Conclusions: Taken together, our results showed that the expression rates for various IHC markers significantly differed between TC and TM. The IHC panel can be useful for differentiation from limited biopsied specimens in daily practice.

Bone morphogenetic protein-7 expression reflects the high proliferative ability and aggressiveness of thymic epithelial tumors

Background

Bone morphogenetic protein-7 (BMP-7) is a transforming growth factor-β superfamily member. We examined whether BMP-7 expression in thymic epithelial tumors is associated with their clinicopathological features.

Methods

One hundred and thirty-two clinical specimens were analyzed in this study. The expression of BMP-7 was detected using immunohistochemistry and was scored as 0, 1, 2, or 3 according to its intensity and was then classified as negative (score 0 and 1) or positive (2 and 3). In addition, Ki-67 staining was performed in type B3 thymoma and thymic cancer.

Results

The positive ratio of BMP-7 was 80% in thymic cancer and 70% in thymoma type B3. In contrast, the positive ratios of BMP-7 in type B2 (29.1%), B1 (3.7%), AB (26%), and A (31%) were relatively low. The mean Ki-67 labeling index of the BMP-7 positive group (10.1%±5.9%) was significantly higher than that of the BMP-7 negative group (4.9%±5.9%) in type B3 thymoma and thymic cancer (P=0.012). The BMP-7 positive group showed significantly poorer overall survival (OS) than the BMP-7 negative group across all patients with thymic epithelial tumors and in all types of thymomas (P=0.006, P=0.018); however, no difference was observed in thymic cancers.

Conclusions

This study showed that high expression of BMP-7 correlated with a poor prognosis in patients with thymic epithelial tumors, and the expression of BMP-7 was higher in type B3 thymomas and thymic cancers than in other types of thymomas. BMP-7 might serve as a novel prognostic biomarker for thymic epithelial tumors.