The nature of cytoplasmic inclusions in cerebellar haemangioblastomas

Stromal cells in cerebellar haemangioblastomas: an immunocytochemical study

The nature of the stromal cells in formalin-fixed paraffin-embedded material from 23 cerebellar haemangioblastomas was investigated using antisera to intermediate filaments (glial fibrillary acidic protein, vimentin and desmin), histiocytic markers (alpha 1-antitrypsin, alpha 1-antichymotrypsin and lysozyme), glycolytic enzymes (alpha and gamma enolase and aldolase C4) and the endothelial markers, factor VIII related antigen and Ulex europaeus I lectin. Most stromal cells stained positively for vimentin and the glycolytic enzymes. Occasional process-bearing cells within the stroma stained strongly for glial fibrillary acidic protein, alpha 1-antitrypsin and alpha 1-antichymotrypsin. No stromal cell staining for desmin, lysozyme or the endothelial markers was observed, although the latter stained the vascular endothelium within all neoplasms. The findings do not support previous suggestions of an endothelial or histiocytic origin for the stromal cells. They appear to be a heterogeneous population including entrapped reactive astrocytes and locally-derived non-angiogenic cells of neuroectodermal (pial) origin.

Immunohistochemical demonstration of alpha-1-proteinase inhibitor in brain tumors

Using light microscopy and immunoperoxidase methods (PAP), the presence of alpha-1-proteinase inhibitor (API) was studied in seventeen brain tumors and four normal brain samples. The brain tumors included four glioblastomas, five low-grade gliomas, two metastatic lung carcinomas, two acoustic schwannomas, and four meningiomas. Normal brain displayed a finely granular intracytoplasmic staining confined to neuronal cells. Glial cells were negative for API. Fifteen of the 17 brain tumors were positive for API. Only two of five low-grade gliomas were negative for API. Glioblastoma and metastatic tumors exhibited the strongest positivity followed by acoustic neuroma, meningioma, and low-grade glioma. All positive samples exhibited finely granular intracytoplasmic API, and 50% exhibited extracellular API positivity. Metastatic and glioblastoma tumors demonstrated prominent extracellular API staining. Our results support the concept of a local production of API by brain tumors.