CD138 (Syndecan-1) in Thymic Neoplasms: Correlation with Various World Health Organization Types and Clinical Outcome
WG Liu, OM Al-Agha, R Chandrasekhar, G Wilding, DF Tan, S Alrawi, T Khoury. State University of New York at Buffalo, Buffalo, NY; Roswell Park Cancer Institute, Buffalo, NY; MD-Anderson, Houston, TX; University of Florida, Jacksonville, FL
Background: The purpose of this study is to investigate the expression of CD138 (Syndecan-1) in thymic neoplasms, and analyze its interrelationship with clinicopathologic variables.
Design: A series of 64 thymic neoplasms were reviewed and classified according to the World Health Organization (WHO) classification system. Key clinical information including Masaoka stage, recurrence free and overall survival was obtained. Staining pattern (cytoplasmic versus membranous) as well as the percentage of positive tumor cells were recorded. A percentage of ≥10% was used as a cutoff for tumor positivity with CD138. Correlation of CD138 expression with WHO type and clinicopathologic variables was statistically analyzed using Fisher's exact test and log-rank test.
Results: 29 of 64 cases (45.3%) stained positive with CD138. Positive staining was seen in 6 of 7 (85.7%) type A, 7 of 15 (46.7%) type AB, 1 of 8 (12.5%) type B1, 1 of 5 (20%) type B2, 11 of 19 (58%) type B3 and 3 of 10 (30%) type C (p=0.04). While 10 of 11 (91%) CD138 positive type B3 had membranous expression; cytoplasmic expression was identified in 6 of 6 (100%) type A, and 6 of 7 (86%) type AB (p < 0.0001). Positive CD138 expression was noted in 19 of 30 (% 63.3) cases with Masaoka stage I (p= 0.01). While negative expression of CD138 was seen in 24 of 34 (71%) cases with advanced Masaoka stages (II, III or IV). Tumor recurred in 4 cases (7%), all of which had negative CD138 expression (p=0.008, log rank test) (Figure 1).
Conclusions: CD138 immunoexpression in thymic neoplasms could be used as an ancillary study to differentiate between WHO histologic types, particularly types A, AB and B3. CD138 negativity can also be used as a predictive factor for worse clinical outcome.
Tuesday, March 23, 2010 1:00 PM
Poster Session IV # 261, Tuesday Afternoon