[1264] Skull Base Chordoma: An Immunohistochemical (IHC) Study of 9 Cases Showing Differentiating Staining from Skull Base Chondrosarcoma

JJ Yang, BM Wenig. St. Luke's-Roosevelt Hospitals, New York; Beth Israel Medical Center, New York

Background: Chordoma is a malignant tumor arising from remnants of the notochord that is most common in the sacrococcygeal region followed by the craniocervical region/skull base and usually can be differentiated from chondrosarcomas by their pathologic and IHC findings, but these tumors may share overlapping findings creating difficulties in their differentiation, especially in biopsy material. Further, the origin for chondroid chordoma remains controversial whether it is a hybrid tumor with chordomatous and cartilaginous differentiation or is a chondrosarcoma variant. The goals of this study were to determine if there are differentiating IHC findings between these tumors and to try and address the issue of classifying chondroid chordoma.
Design: We identified 9 cases of skull base chordomas and 7 cases of skull base chondrosarcomas from our files over a 5-yr period (2005-09); the clinical and pathologic features were reviewed. IHC staining included cytokeratins (AE1/AE3, CAM 5.2), EMA, p63, brachyury, D2-40, S100 protein, vimentin, NSE, GAL-3, GFAP and VEGF.
Results: Chordomas included 6 females and 3 males ranging in age from 8 to 58 years (median, 48 years). These tumors include conventional chordoma (n=7), chondroid chordoma (n=1) and dedifferentiated chordoma (n=1). All chordoma subtypes were immunoreactive for cytokeratins (AE1/AE3, CAM5.2), EMA, S100 protein, brachyury, and vimentin, and were negative for D2-40. Chondrosarcomas included 5 males and 2 females ranging in age from 51-62 yrs (median 58 yrs). All chondrosarcomas were histologically low-grade (Grade I) and included one case of a clear cell type. The chondrosarcomas were immunoreactive for D2-40, S100 protein and vimentin but negative for epithelial markers and brachyury.
Conclusions: Based on our study, skull base chordomas have a distinct IHC antigenic profile contrasting with that of skull base chondrosarcomas. The chordomas consistently expressed epithelial markers and brachyury but were negative for D2-40 while the chondrosarcomas were consistently reactive for D2-40 but negative for epithelial markers and brachyury. Both tumor types expressed S100 protein and vimentin. The results of our findings provide a mechanism for differentiating chordomas from chondrosarcomas, affirm that chondroid chordoma approrpiately be classified within the spectrum of chordomas and support the development of chordomas from the notochord.
Category: Head & Neck

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 165, Wednesday Morning


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