Pathology

1. Neurofibromata
   • Benign tumour derived from peripheral nerve elements
   • Histologically consist of Schwann cells (appears as bundle of elongated wavy spindle cells)
   • Associated with collagen fibrils and myxoid material
   • Often not encapsulated (cf neurilemmas - the other common benign tumour of peripheral nerves - which are always encapsulated)
2. Neurofibromatosis
   • Multiple neurofibromata in a patient in combination with other dermatological manifestations (6 cafe au lait spots)
   • Autosomal dominant inheritance
   • Type I: Von Reckinghausen's disease: Chromosone 17
   • Type II: Bilateral acoustic neuromas: Chromosome 22. Variable penetrance. Cutanous signs less seen.

Approach

• Examine as for any lump

Neurofibroma

Plexiform neurofibroma

1. Inspect
   • May be solitary or multiple
   • Pedunculated nodule
   • If arising from deeper nerves can result in severe deformity due to diffuse enlargement of the peripheral nerve with involvment of the skin (plexiform neurofibroma)
   • Associated cafe au lait spots
2. Palpate
   • Soft / fleshy in consistency

Completion

1. Ask how lump affects life
2. If Multiple neurofibromata
   • Test cranial nerves (esp VIII - Type 2, bilateral acoustic neuromas)
   • Measure the BP (associated phaeochromocytoma)

Complications of Neurofibroma

1. Direct pressure effects: spinal cord / root compression
2. Deafness (if VIII involved)
3. Sarcomatous transformation - occurs only in Von Reckinghausen's disease in 5-13% of cases)
4. Intra-abdominal effects - obstruction, chronic GI bleeds
5. Skeletal changes - can cause kyphoscoliosis, cystic changes and pseudoarthrosis

Treament options

1. Non-surgical
   • Leave alone if asymptomatic and patient does not want intervention
2. Surgical: only indicated if malignant growth suspected
   • Post excision regrowth is common
   • Neurofibromata cannot be surgically detached from the underlying nerve