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Neurofibromatosis
is an autosomal dominant disorder producing tumors along the course
of nerves and occasionally resulting in marked soft tissue or bony
deformity. Diagnosis is clinical. There is no specific treatment,
but tumors can be removed surgically.
Neurofibromatosis has 2 forms. Type 1 (von Recklinghausen's disease) is most prevalent, causing neurologic, cutaneous, and sometimes orthopedic manifestations. Type 2 accounts for 10% of cases, manifesting primarily as congenital bilateral acoustic neuroma.
Neurofibromas are benign tumors consisting of Schwann cells and neural fibroblasts. Peripheral neurofibromas develop anywhere along the course of peripheral nerves. Most appear during adolescence. There are 4 types. Cutaneous neurofibromas are soft and fleshy; subcutaneous neurofibromas are firm and nodular. Nodular plexiform neurofibromas may involve spinal nerve roots, typically growing through an intervertebral foramen to produce intraspinal and extraspinal masses (dumbbell tumor). The intraspinal part may compress the spinal cord. Diffuse plexiform neurofibromas can be disfiguring and may produce deficits distal to the neuroma. Plexiform neurofibromas can undergo malignant transformation. There are 2 types of central (cranial nerve) neurofibromas: optic gliomas, which may cause progressive blindness, and acoustic neuromas (vestibular schwannomas), which may cause dizziness, ataxia, deafness, and tinnitus. Optic gliomas occur in type 1 neurofibromatosis, whereas acoustic neuromas occur in type 2 neurofibromatosis.
Symptoms and Signs
Type 1:
With type 1, most patients are asymptomatic and identified during routine examination, examination for cosmetic complaints, or when evaluating a positive family history. Some present with neurologic symptoms or bony abnormalities. In > 90%, characteristic skin lesions are apparent at birth or develop during infancy. Lesions are medium-brown (café-au-lait), freckle-like macules, distributed most commonly over the trunk, pelvis, and flexor creases of elbows and knees. During late childhood, flesh-colored cutaneous tumors of various sizes and shapes appear, ranging in number from several to thousands. Rarely, plexiform neuromas (subcutaneous nodules or amorphous overgrowth of underlying bone or Schwann cells) develop, producing an irregularly thickened, distorted structure with grotesque deformities.
Neurologic symptoms are varied but relate to location and number of neurofibromas. Skeletal anomalies include fibrous dysplasia, subperiosteal bone cysts, vertebral scalloping, scoliosis, thinning of the long-bone cortex, pseudarthrosis, and absence of the greater wing of the sphenoid bone (posterior orbital wall), with consequent pulsating exophthalmos. An optic glioma and Lisch nodules (iris hamartomas) occur in some patients. Some children have learning problems and slightly larger heads.
Type 2:
In type 2, bilateral acoustic neuromas develop and become symptomatic in childhood or early adulthood. They cause hearing loss and unsteadiness, and sometimes headache or facial weakness. Bilateral 8th cranial (vestibulocochlear) nerve masses may be present. Family members may have gliomas, meningiomas, or schwannomas.
Diagnosis
and Treatment
Diagnosis is clinical (see Table 1: Neurologic Disorders in Children: Diagnosing Neurofibromatosis ). CT or MRI may detect 8th cranial nerve masses in type 2; MRI may show focal density changes in type 1. Genetic testing is not routinely available.
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Table 1
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Diagnosing Neurofibromatosis
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Type
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Criteria
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1
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Two or more of the following must be present:
≥ 6 café-au-lait macules with a diameter at the widest point of > 5 mm in prepubertal patients and > 15 mm in postpubertal patients
≥ 2 neurofibromas of any type or 1 plexiform neurofibroma
Freckling in the axillary or inguinal region
≥ 2 Lisch nodules (iris hamartomas)
A distinctive osseous lesion (eg, sphenoid dysplasia or thinning of long-bone cortex), with or without pseudarthrosis
A parent, sibling, or child with diagnosed type 1 neurofibromatosis
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2
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One of the following must be present:
Bilateral 8th nerve masses seen with CT or MRI
A parent, sibling, or child with type 2 neurofibromatosis and either a unilateral 8th nerve mass or any 2 of the following: neurofibroma, meningioma, glioma, schwannoma, or juvenile posterior subcapsular lenticular opacity
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Adapted from Martuza RL, Eldredge R: Neurofibromatosis 2 (bilateral acoustic neurofibromatosis). Reprinted by permission of The New England Journal of Medicine 318:684–688, 1988.
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No general treatment is available. Neurofibromas that produce severe symptoms may require surgical removal or irradiation, although surgery may obliterate function of the involved nerve. Genetic counseling is advisable. If either parent has neurofibromatosis, risk to subsequent offspring is 50%; if neither has it, subsequent risk is unclear because new mutations are common.
Last full review/revision November 2005
Content last modified November 2005
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