Immunohistological characterization of the tumour – brain boundary in craniopharyngiomas

Objectives: Craniopharyngiomas (CP) are benign epithelial tumours of the sellar region. However, brain invasion by small, finger like protrusions into adjacent brain structures i.e. the hypothalamus and basal ganglia, is often associated with tumour recurrence and cause serious clinical symptoms, including obesity. Methods: Herein, we immunohistochemically characterized the interface between tumour and surrounding brain tissue in 49 CP (40 adamantinomatous and 9 papillary) compared to other non-neuroepithelial tumours (12 meningiomas, 18 metastatic tumours of the CNS and 12 cavernous haemangiomas) using a panel of following antibodies: glial fibrillary acid protein (GFAP), Vimentin (intermediate filament proteins), Nestin (early intermediate filament protein), Map2 (microtubule associated protein) and Tenascin C (embryonal extracellular matrix molecule). Results: We identified a novel cell population characterized by GFAP/MAP2 and Nestin co-expression within the invasion niche of adamantinomatous CP (adaCP). A similar population of presumably astroglial precursors were not visible in the other tumour entities. Conclusion: Our data support the hypothesis that adaCP unlike other non-neuroepithelial tumours of the CNS create a tumour specific cellular environment, especially at the invasion border of tumour cells into the surrounding brain tissue. Whether this is a consequence of an increased Wnt-signalling pathway detectable in 90% of this tumour entity and the cause of infiltrative growth, is under further study.