Origin: Schwannomas originate from schwann cells, which are glial cells that produce the myelin sheath around nerves in the peripheral nervous system.
Benign nature: Most schwannomas are benign (non-cancerous) and slow-growing. Malignant transformation is rare.
Histopathology:
1. Schwannomas exhibit a biphasic pattern with dense antoni A areas and looser antoni B areas.
• Antoni A areas (compact and cellular with a fascicular pattern)
• Antoni B areas (looser and less cellular with a myxoid background).
2. Verocay bodies:
• They are characterized by two compact rows of aligned nuclei, which are separated by a central area that is acellular and fibrillar. These bodies are a key feature used to identify schwannomas.
• The Verocay bodies are typically found in antoni A areas.
Genetic association: Most schwannomas are sporadic, but they can be associated with neurofibromatosis type 2 (NF2), a genetic disorder where patients often develop multiple schwannomas.
NOTE: NF2 gene is located on chromosome 22 and encodes a protein called merlin (schwannomin).
Reference:
1. Robbins & Cotran pathologic basis of disease (South asia edition), Vol. 2