Neurocutaneous Syndromes Flashcards
What are the 3 subtypes of neurofibromatosis?
NF1, NF2, and schwannomatosis
What is the most common type of neurofibromatosis?
NF1 (90%)
What is the gene involved and mode of inheritance for NF1?
NF1 gene (neurofibromas), AD –> negatively regulates Ras activations
-50% are sporadic mutations and mosaic/segmental dz can occur
Diagnostic criteria for NF1?
Must have >2 of the following:
- Six café-au-lait macules >0.5cm prepubertal or >1.5cm postpubertal
- intertriginous freckling
- Plexiform neurofibroma or >2 dermal neurofibromas
- >2 lisch nodules
- Optic nerve glioma
- Pathogenic skeletal dysplasia (tibial or sphenoid wing dysplasia)
- Affected first-degree relative
What NF1 findings occur in infancy?
Café-au-lait macules, plexiform neurofibromas, neurologic findings, macrocephaly, tibial dysplasia, sphenoid wing dysplasia
What findings of NF1 occur in the prepubertal stage?
Intertriginious freckling, optic gliomas, brainstem gliomas meningiomas, scoliosis
What are the cutaneous findings in NF1?
Neurofibroma: soft papule that invaginates upon finger pressure (buttonholing)
- Plexiform neurofibroma: overlying CALM and/or hypertrichosis, feels like a “bag of worms” texture seen in 25% of patients
- Malignant peripheral nerve sheath tumor (MPNST): rapid enlargement or pain of plexiform neurofibroma (10% risk)
- CALM (typically >6, increased size and number if first 5 years
- Axillary freckling (Crowe’s sign)
Skeletal manifestations of NF1?
Sphenoid wing dysplasia: pulsating exophthalmos can be noted, though often asymptomatic
- macrocephaly
- scoliosis
- congenital tibial pseudarthroses
- additional skeletal abnormalities: thoracic cage asymmetry, osteoporosis, and pathological fractures
- short stature
Neurologic manifestations of NF1?
Learning disabilities, autism, ADHD
- seizures
- hydrocephalus
- Optic glioma which can lead to blindness; seen w/ precocious puberty, astrocytomas, meningiomas, vestibular/acoustic schwannoma/neuroma, ependymoma
What other neoplasms can be seen in NF1?
Neurofibrosarcoma, rhabdomyosarcoma, pheochromocytoma, Wilms’ tumor and CML
- Nevus anemicus found in up to 50% of patients
- TRIPLE ASSOCIATION W/ NF1, JUVENILE XANTHOGRANULOMAS, AND JMML
What is the most common second mutation seen in neurofibroma to cause malignant transformation?
p53
What is the inheritance pattern and gene involved in NF2?
AD, mutations in SCH (schwannomin/merlin) which is a tumor supressor gene
What are the cutaneous findings in NF2
neurofibromas (lower #’s than NF1), more commonly subcutaneous type w/ overlying pigment/hair rather than intradermal. can have CALMS too
Neurologic findings in NF2?
Bilateral vestibular schwannomas (acoustic neuromas) is diagnostic –> deafness, tinnitus, unsteadiness, headache, meningiomas, astrocytomas and ependymas
Most common cause of death in NF2?
CNS tumors
Ocular findings in NF2?
Juvenile posterior sub capsular lenticular opacity/cataract
What are the genetics and genes associated with tuberous sclerosis complex?
AD, mutations in hamartin (TSC1) or tubers (TSC2) [tumor supressors]
What is the pathophysiology of tuberous sclerosis?
Tuberin and hamartin form complex that inhibit signal transduction of downstream efforts of mTOR –> results in abnormal cellular differentiation, proliferation and migration –> hamartomas
What are the main cutaneous findings of tuberous sclerosis?
Adenoma sebaceum (facial angiofibromas), hypopigmented “ash-leaf” macules (confetti pattern pretibially; first cutaneous finding), shagreen patch (which is a connective tissue nevus), periungual fibromas (“Koenen tumors”), and cafe au lait macules
What is the histology of the angiofibromas?
Dermal fibrosis w/ stellate fibroblasts, atrophic sebaceous glands, dilated capillaries, and loss of elastin
What is the histology of the shagreen patch?
Connective tissue nevus –> broad sclerotic collagen bundles and reduced elastin