Distribution of Lysosome-Associated Membrane Proteins-1 and -2, and Cathepsin D in Eosinophilic Granular Bodies: Possible Relationship to Cyst Development in Pilocytic Astrocytomas

Pilocytic astrocytomas are usually cystic; cyst formation within these tumours may result in increased intracranial pressure, due to the effect of their mass, and contribute to cerebral damage. Eosinophilic granular bodies (EGBs) are produced abundantly in pilocytic astrocytomas but their role in disease progression remains unknown. Immunohistochemistry studies showed EGBs to exhibit pronounced reactivity to antibodies against lysosome-associated membrane proteins (LAMP)-1 and LAMP-2, and the lysosomal enzyme cathepsin D. Both LAMP-1 and LAMP-2 showed peripheral rim and granular staining patterns. The EGBs were scattered widely across cysts and, where EGBs aggregated in clusters, were usually close to areas of fluid in the cysts. Most EGBs had nuclei either attached or close by, indicating that the EGBs may be derived from anucleated astrocytes. The results suggest that EGBs, together with other factors, may play a role in the development of cysts in pilocytic astrocytomas.