TABLE 4.
Tumor Subtype | Histology & Ultrastructure (EM) | Immunoreactivity | Distinguishing Features |
---|---|---|---|
All | TTF-1 (strong nuclear immunoreactivity)16,22 S100 (variable staining) |
||
SCO | Spindle or epitheloid cells in intertwining fascicles w/ granulated eosinophilic cytoplasm; abundant mitochondria by EM | EMA (strong) GFAP (rarely positive) |
Increased tendency to bleed during the op |
Pituicytoma | Fibrillary cells arranged in fascicles w/ elongated nuclei; abundant intermediate filament processes by EM | EMA (variable) GFAP (positive generally) |
|
Granular cell tumor | Polygonal cells w/ central nuclei & PAS-positive, granular cytoplasm; abundant lysosomes by EM | EMA (variable) GFAP (rarely positive) |
EM = electron microscopy; PAS = periodic acid-Schiff.