Neurilemmoma

Introduction

A benign encapsulated tumor composed of Schwann cells
- tumor is well encapsulated on the surface of a peripheral nerve
- also known as Schwannoma
Age & location
- peak incidence is in the 3rd to 6th decades
  - previous test question ages: 40, 45
- affect males and females equally
- often occurs on flexor surfaces of extremities and head and neck
- larger lesions may occur in the pelvis
Pathoanatomy
- can affect motor or sensory nerves
Genetics
- often associated with mutations affecting NF2 gene
Malignant transformation
- extremely rare

Presentation

Symptoms
- usually asymptomatic
- may have paresthesia in the distribution of the peripheral nerve
Physical exam
- may have positive Tinel’s sign in the distribution of the nerve affected may be present

Imaging

Histology

Gross pathology
- the lesion is well encapsulated in a nerve sheath
- gray in color
Histology
- Antoni A structure
  - a pattern of spindle cells arranged in intersecting bundles (spindle cell battle formation)
- Antoni B
  - areas with less cellularity with loosely arranged cells
- Verocay bodies
  - pathognomonic
  - composed of two rows of aligned nuclei in a palisading formation
Immunochemistry
- strongly uniform S100 antibody staining

Treatment