Grumose or foamy spheroid bodies involving astrocytes in the human brain.

Grumose or foamy spheroid bodies (GFSB), which correspond to the classical pathological description, 'grumose degeneration', are described. By light microscopy, GFSB are faintly eosinophilic and spheroidal structures with a foamy appearance in haematoxylin and eosin stains; they vary from 10 to 50 microns in diameter and contain amorphous debris-like material. Some GFSB, however, contain a varying amount of eosinophilic grumose aggregates, some of which are randomly stained with periodic acid Schiff (PAS), Schmorl, Berlin blue, Grimelius or silver methods. The Gallyas stain, on the other hand, usually stains the contents of GFSB black or brown. Immunohistochemically, most GFSB are ubiquitin-positive. Characteristically glial fibrillary acidic protein is associated with some GFSB giving a foamy appearance. Ultrastructurally, GFSB consist of dense bodies of various sizes and configuration. Glial fibrillary bundles and astrocytic punctate adhesions are occasionally observed associated with GFSB. Anatomically, GFSB are observed preferentially in the rostroventral parts of both the substantia nigra pars reticulata and the globus pallidus in a number of human neurodegenerative diseases and aged brains. GFSB, however, appear outside the above regions in various circumstances such as trauma, infarction and astrocytomas. In conclusion, GFSB are ubiquitinated structures closely related to astrocytes in their formation and with a preferred location in the deep regions of the basal ganglia.