Gliosis

Epidemiology:

Common sites:

Gross features:

Histologic features:

• increased number and density of astrocytes
• expanded cytoplasm
• bright pink
• somewhat irregular
• increased cellular processes
• eccentric nucleus
• eccentric
• enlarged
• vesicular
• prominent nucleolus
• no expanding border (although may surround a tumour)
• relatively uniform spacing of reactive astrocytes (compared to glioma)
• Longstanding lesions:
• Small, dark nuclei
• Dense net of cellular processes (glial “fibrils”)
• Rosenthal fibres (not specific):
• Thick, elongated, brightly eosinophilic structures with somewhat irregular contour

Immunophenotype:

Marker:	Sensitivity:	Specificity:
Phosphotungstic acid hematoxylin (PTAH)
GFAP	More sensitive

Molecular features:

Other features:

• evident on H&E or PTAH by 3 weeks after injury