neurofibromatosis

Question 1

diagnosis

Answer 1

NF1 (von Recklinghausen’s disease)
Diagnosis is made if 2 of the following are found:
1 ≥6 café-au-lait macules >5mm (pre-pubertal) or >15mm (post-pubertal) 2 ≥2 neurofibromas of any type or 1 plexiform
3 Freckling in the axillary or inguinal regions
4 Optic glioma
5 ≥2 Lisch nodules
6 Distinctive osseous lesion typical of NF 1, eg sphenoid dysplasia
7 First-degree relative with NF 1 according to the above criteria

NF2
Diagnosis is made if either of the following are found:
1 Bilateral vestibular Schwannomas seen on MRI or CT 2 First-degree relative with NF2, and either:
a) Unilateral vestibular Schwannoma; or
b) One of the following:
• Neurofibroma
• Meningioma
• Glioma
• Schwannoma
• Juvenile cataract (NF2 type)

Question 2

inheritance

Answer 2

both NF1 and NF2 have autosomal dominant inheritance

Question 3

risk factors for NF 1

Answer 3

• familial history

- severe crush injury

Question 4

investigations

Answer 4

1st investigations:

• MRI and/or CT
• PET scan
• biopsy (May help to define the presence, nature, and/or extent of lesion(s) such as neurofibroma or malignant peripheral nerve sheath tumours)
• genetic testing to identify mutation in NF1 locus

Question 5

symptoms

Answer 5

FOR NF1

Local effects of neurofibromas: Nerve root compression (weakness, pain, paraesthesiae)
GI— bleeds, obstruction
bone—cystic lesions, scoliosis, pseudarthrosis.
raised BP (6%) from renal artery stenosis or phaeochromocytoma. Plexiform neurofibromas (large, sub- cutaneous swellings).
Malignancy (5% patients with NF1): optic glioma, sarcoma- tous change in a neurofibroma. Epilepsy risk increased (slight). Rare association: carcinoid syndrome

FOR NF2

Café-au-lait spots are fewer than in NF1.

Bilateral vestibular Schwannomas (= acoustic neuromas) are characteristic, becoming symptomatic by ~20yrs old when sensorineural hearing loss is the 1st sign. There may be tinnitus and vertigo. The rate of tumour growth is unpredictable and variable. The tumours are benign but cause problems by pressing on local structures and by raised ICP. They may be absent in mosaic NF2. Juvenile posterior subcapsular lenticular opacity (a form of cataract) occurs before other manifestations and can be useful in screening those at risk.