Distinguishing hemangioblastomas from metastatic clear-cell renal cell carcinomas (CCRCCs) in the brain is a diagnostic challenge owing to similar clinical and morphologic presentations. Inhibin-alpha and aquaporin1 were shown as positive markers of hemangioblastoma, but are not totally reliable distinguishing hemangioblastoma from metastatic CCRCC. This study shows that the diagnosis can be achieved using a combination of markers. To identify the panel of markers useful for this differential, 67 hemangioblastomas and 34 metastatic CCRCCs were analyzed using a panel of antibodies including aquaporin1, inhibin-alpha, D2-40, cytokeratin AE1/AE3, epithelial membrane antigen, and CD10. The study confirms the usefulness of aquaporin1 (97% sensitivity, 83% specificity) and inhibin-alpha (88% sensitivity, 79% specificity) as positive markers of hemangioblastoma and shows that aquaporin1 is a superior positive marker versus inhibin-alpha for the differential. Positivity of tumor cells with cytokeratin AE1/AE3 is the signature of a metastatic CCRCC (100% specificity, 88% sensitivity) and CD10 expression as well (100% specificity, 79% sensitivity). The combined use of aquaporin1 and AE1/AE3 yields a high degree of sensitivity and specificity to differentiate between hemangioblastoma and metastatic CCRCC. All tumors but one aquaporin1 positive and cytokeratin AE1/AE3 negative (65/66) correspond to hemangioblastomas (97% sensitivity, 97% specificity, 98.5% diagnostic positive predictive value). Tumors with the opposite profile, aquaporin1 negative, and cytokeratin AE1/AE3 positive, (25/25), correspond to metastatic CCRCC (74% sensitivity, 100% specificity, 100% diagnostic positive predictive value). In summary, aquaporin1 is the most sensitive positive marker of hemangioblastoma. Despite its moderate specificity, when used in combination with epithelial marker AE1/AE3, it allowed to reliably distinguish hemangioblastoma from metastatic CCRCC.
"On the other hand, a negative staining for chromogranin or synaptophysin generally excludes the hypothesis of adrenal carcinoma and paraganglioma, which stain positively for these proteins . Nevertheless, in some cases the distinction between renal carcinoma and HBL may be challenging even by using immunohistochemistry. Indeed, focal EMA and CD10 stains have been noted in renal HBL [48, 56]; in addition, renal cell carcinoma with rhabdoid features may show diffuse staining for NSE, focal staining for EMA and S100 protein, and reduced cytokeratins expression . "
[Show abstract][Hide abstract] ABSTRACT: Brachyury is a transcription factor which is required for posterior mesoderm formation and differentiation as well as for notochord development during embryogenesis. Due to its expression in the neoplastic cells of chordoma, a malignant tumour deriving from notochordal remnants, but not in tumors showing a similar histology, brachyury has been proposed as a diagnostic marker of this neoplasia. Though commonly considered a hallmark of chordoma, the expression of brachyury has been also documented in the stromal cells of hemangioblastoma (HBL), a slow growing tumor which may involve the central nervous system (CNS) and, rarely, the kidney. Herein we review the role of brachyury immunohistochemical detection in the identification and differential diagnosis of chordoma and HBL towards histological mimickers and suggest that brachyury is added to the panel of immunohistochemical markers for the recognition of HBL in routinary practice, principally in unusual sites.
[Show abstract][Hide abstract] ABSTRACT: Diagnostic neuro-oncology practice has benefited in the last 2 decades from the incorporation of, and recent advances in,
immunohistochemistry (IHC). Although the mainstay of brain tumor diagnosis including its grading remains conventional hematoxylin-eosin
(H&E)-stained histology, it is no doubt that IHC plays a major role in differential diagnosis and in improving the diagnostic
accuracy. It is generally used for purposes of (1) identifying tumor cell type/origin, (2) assessing cell proliferation potential,
(3) evaluating the boundary between tumor and the surrounding tissue (i.e., tumor “margin”), and (4) excluding reactive processes
(e.g., demyelinating and infectious diseases). In the future, novel antibodies utilized as prognostic, predictive markers
and as potential therapeutic targets for brain tumors will be developed.
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