Neurofibromatosis

Question 1

What is the other name for neurofibromatosis type 1

Answer 1

von Recklinghausen’s disease

Question 2

Describe the inheritance pattern of neurofibromatosis type 1

Answer 2

Autosomal dominant

Question 3

What is the gene locus for NF1

Answer 3

17q11.2

Question 4

What are some signs of NF1

Answer 4

Cafe-au-lait spots - flat, coffee coloured patches of skin seen in 1st year of life - clearest in UV light, increasing in size and number with age. Adults have typically >6, >15mm

Freckling - in skin folds - axillae, groin, sub mammary area usually present by age 10

Dermal neurofibromas - small violaceous nodules gelatinous in texture which appear at puberty and become papillomatous. They are not painful but might itch

Nodular neurofibromas - arise from nerve trunks. Firm and clearly demarcated they can give rise to paraesthesia if pressed

Lisch nodules - tiny harmless regular brown/translucent mounds on the iris, <2mm in diameter. Develop by age 6

Short stature

Macrocephaly

Question 5

List the complications of neurofibromatosis type 1

Answer 5

Mild learning disability
Local effects of neurofibromas - nerve root compression, GI bleed and obstruction, bone lesions, scoliosis, HTN from renal artery stenosis or pheochromocytoma
Epilepsy
Malignancy - carcinoid syndrome, optic gliomas, sarcomatous change of the neurofibroma

Question 6

How is neurofibromatosis treated?

Answer 6

MDT approach
Yearly cutaneous survey and BP measurement
Excision of neurofibromas if troublesome
Genetic counselling

Question 7

Describe the inheritance pattern of NF2

Answer 7

Autosomal dominant, though 50% de novo, with mosaicism in some

Question 8

List the signs of NF2

Answer 8

Cafe-au-lait spots - fewer than in NF1

Bilateral vestibular schwannoma - sensorineural hearing loss by age 20, benign, problems due to compression of local structures and increased ICP

Juvenile posterior subcapsular lenticular opacity - cataracts, occurs before other manifestations so can be used to screen those at risk

Question 9

What are the complications of NF2

Answer 9

Tender schwannomas of peripheral or cranial nerves

Menignomas

Question 10

How is NF2 managed?

Answer 10

Hearing tests yearly from puberty in affected families with MRI brain if abnormality detected
Vestibular schwannoma treatment - neurosurgical and complicated by hearing loss and facial palsy

Question 11

What is the mean survival of vestibular schwannoma from diagnosis?

Answer 11

15yrs