Granular cell change in astrocytic tumors.

Intracerebral granular cell neoplasms are uncommon. We report five hemispheric astrocytomas, all of which showed the distinctive features of granular cell change, being composed exclusively or predominantly of rounded cells with coarse granular eosinophilic cytoplasm and eccentrically placed nuclei. Four showed clear foci of transition from an anaplastic astrocytoma and contained lipidized as well as granular cells. In all tumors, the cytoplasmic granules were positive for periodic acid Schiff and resistant to diastase digestion, and there was focal glial fibrillary acidic protein expression. In addition, diffuse cytoplasmic positivity with epithelial membrane antigen antiserum was present, but in no case was there true membrane staining. Ultrastructural appearances were similar in four cases, showing the cytoplasm of tumor cells to be filled with membrane-bound autophagic vacuoles; bundles of intermediate filaments were also seen in some cells. Despite earlier controversy over the histogenesis of granular cell tumors, it is now clear that granular change is a degenerative phenomenon that, like lipidization, can occur in tumors of different cell types, including--rarely--astrocytic neoplasms. It is important that this histologic variant be recognized, as on a small biopsy sample diagnostic confusion with an infarct, demyelinating disease or a secondary carcinoma is a real possibility.