Immunophenotype of Myxopapillary Ependymomas

Abstract

Myxopapillary ependymoma (MPE) is a slow-growing tumor occurring almost exclusively in the region of conus medullaris, cauda equina, and filum terminale. On microscopic examination, some of these tumors show solid sheets of cells with an epithelioid morphology mimicking a metastatic carcinoma. Several immunohistochemical studies addressed this issue with discordant results. We report the immunohistochemical findings of 9 additional cases of MPE. From 2004 to 2011, a total of 9 cases of MPE were recorded in our surgical pathology files. The histologic material and clinical data were reviewed for each case. There were 6 female and 3 male patients. The ages ranged from 15 to 58 years (mean, 31 y). Eight cases were intradural, lumbosacral (L1-S1), and 1 case was located in the sacrum. All tumors expressed CD99 and GFAP (100%). Eight tumors were positive for CD56 (89%). All tumors (100%) expressed focally CKAE1/AE3. One tumor (11%) was focally positive for CK8/18 and CK7. D2-40 was focally positive in 1 case (11%). PLAP and AFP were both negative in all cases. Synaptophysin was focally positive in 1 case. NSE was positive in all cases. All tumors were negative for CK5/6, CK20, E-cadherin, and TTF-1. Our study shows that the vast majority of MPE are positive for CD99, CD56, and GFAP. In selective cases, especially when the material obtained for pathologic evaluation is scanty and the tumor displays epithelioid appearance, the diagnosis may be challenging owing to cytokeratin positivity suggesting metastatic carcinoma. However, the clinical and radiologic features in addition to the positivity for GFAP should prompt pathologists to consider MPE in the differential diagnosis of such cases. Interestingly, we found that MPE are positive for NSE, which suggests a neuroglial differentiation.

Pediatric Extraspinal Subcutaneous Sacrococcygeal Myxopapillary Ependymoma: Case Report and Minireview

“…16,17 MPE is usually positive for CD99, CD56, and GFAP. 18 Podoplanin is not expressed in our case. This is different from the expression pattern previously reported.…”

Utility of brachyury in distinction of chordoma from cytomorphologic mimics in fine‐needle aspiration and core needle biopsy

“…Brachyury is also negative in myxopapillary ependymoma, a diagnostic consideration in sacral locations . Myxopapillary ependymoma is positive for S‐100 and GFAP, and can show at least focal cytokeratin positivity, thus brachyury is useful in the distinction between myxopapillary ependymoma and chordoma. Myoepithelial tumors of soft tissue typically show heterogeneous expression of S‐100, GFAP, keratin, EMA, and SMA, and may mimic chordoma when a myxoid stroma is predominant.…”

“…Brachyury staining is absent in soft tissue mixed tumor/myoepithelioma, and careful histologic examination will also help distinguish myoepithelial neoplasms from chordoma. Lastly, the survey studies examining brachyury expression in large numbers of neoplasms have reported an absence of staining in the majority of entities tested, including osteosarcoma, synovial sarcoma, chondromyxoid fibroma, chondroblastoma, extraskeletal myxoid chondrosarcoma, myxoid liposarcoma, rhabdomyosarcoma, pleomorphic adenoma, mucoepidermoid carcinoma, melanoma, and urothelial, breast, and ovarian carcinoma . While one study reported brachyury expression in non‐neoplastic testis and a second study found positive staining in a small subset of germ cell tumors, a subsequent larger series reported no staining in 111 germ cell tumors and non‐neoplastic testis samples …”

Immunohistochemical features of giant cell ependymoma of the filum terminale with unusual clinical and radiological presentation

“…Our aim was to test other IHC markers that have been studied in non-giant cell ependymomas and that could possibly be extrapolated to our case. Based in a study published by Lamzabi et al [21] in myxopapillary ependymomas that expressed CD99 in all cases and CD56 was diffusely positive in 88% cases, we attempted the technique. Other IHC studies have analyzed the expression of bcl-2, p53 and cyclin D1 in ependymomas and they appear to act as prognostic predictors although results are discordant [22].…”