Pathology | Retroperitoneum II - [click on image(s) below]
Neurilemmoma (Schwannoma)
Schwann cell are derived from neural crest cells and migrate peripherally as nerves form from spinal ganglia. They orient themselves parallel to the axons and encase the axons with their cytoplasm.
Clinical: male = female; 20-50 years; head/ neck and flexor surfaces of the extremities >> retroperitoneum, mediastinum; usually single, slow-growing, and rarely have pain or other neurological symptoms.
Gross: Surrounded by a true capsule; may be small fusiform lesions or large eccentric masses; pink-white; retroperitoneal tumors are larger and often show degenerative changes like cystic change and calcification.
Histologic features:
the hallmark of the schwannoma (above, left) is alternating areas of cellular (Antoni A) and hypocellular (Antoni B) areas; cells have twisted or wavy nuclei and indistinct cytoplasmic borders
Verocay bodies are also common: consist of palisading nuclei that form two compact rows separated by fibrillary pink cytoplasm (above, right)
Immunohistochemistry: S-100 positive
Treatment: excision; malignant change is exceedingly rare.
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