(VON RECKLINGHAUSEN’S DISNEUROFIBROMATOSISEASE)
NEUROFIBROMATOSIS (VON RECKLINGHAUSEN’S DISEASE)
- Neurofibromatosis type 1 (NF1) and type 2 (NF2) are neurocutaneous disorders inherited as autosomal dominant genetic syndromes..
Neurofibromatosis type 1
- The clinical criteria used to diagnose NF1 are as follows, in the absence of alternative diagnoses:
- Six or more café-au-lait spots or hyperpigmented macules =5 mm in diameter in prepubertal children and 15 mm postpubertal
- Axillary or inguinal freckles (>2 freckles)
- Two or more typical neurofibromas or one plexiform neurofibroma
- Optic nerve glioma
- Two or more iris hamartomas (Lisch nodules), often identified only through slit-lamp examination by an ophthalmologist
- Sphenoid dysplasia or typical long-bone abnormalities such as pseudarthrosis
- First-degree relative (eg, mother, father, sister, brother) with NF1.
Neurofibromatosis type 2
- It is a genetic disorder marked by the predisposition to develop a variety of tumors of the central and peripheral nervous systems. In contrast to neurofibromatosis type 1 (NF1), NF2 produces a paucity of cutaneous manifestations.
- Clinical diagnosis of NF2 requires that an individual present with at least 1 of the following clinical scenarios :
- Bilateral vestibular schwannomas
- A first degree relative with NF2 and Unilateral vestibular schwannoma or Any two of: meningioma, schwannoma, glioma, neurofibroma, posterior subcapsular lenticular opacities
- Unilateral vestibular schwannoma and Any two of: meningioma, schwannoma, glioma, neurofibroma, posterior subcapsular lenticular opacities
- Multiple meningiomas and Unilateral vestibular schwannoma or Any two of: schwannoma, glioma, neurofibroma, cataract.
Difference b/w Schwannoma & Neurofibroma
Schwannoma (or Neurilemmoma)
- are true encapsulated neoplasm composed of schwann cells.
- It compresses the nerve of origin.
- There is a plane of cleavage separating the nerve from the mass.
Neurofibroma
- are unencapsulated benign neoplasm of schwann cells and fibroblasts.
- The tumor involves the nerve. Grossly it appears as expanded nerve.
- It is composed of mixture of schwann cell and fibroblast and contains axons within it.
- It can not be demarcated from the nerve therefore can not be removed without sacrificing the nerve.
Difference between NF-1 and NF-2:
|
Feature |
NF1 |
NF2 |
|
Mutation |
NFl gene on chromosome 17 causes |
NF2 gene on chromosome 22q. |
|
|
von Recklinghausen’s disease. The NFl |
NF2 encodes a protein called |
|
|
gene is a tumor-suppressor gene; it encodes a protein, neurofibromin |
neurofibromin 2, schwannomin,or merlin |
|
Cutaneous feat |
cutaneous neurofibromas, pigmented lesions of the skin called café au lait spots, freckling in non-sun-exposed areas such as the axilla, hamartomas of the iris termed Lisch nodules, and pseudoarthrosis of the tibia |
Multiple café au lait spots and peripheral neurofibromas occur rarely |
|
Complications |
Aqueductal stenosis with hydrocephalus, scoliosis, short stature, hypertension, epilepsy, and mental retardation may also occur. |
A characteristic type of cataract, juvenile posterior subcapsular lenticular opacity, occurs in NF2 |
|
Neurological features |
Patients with NF1 are at increased
risk of developing nervous system neoplasms, including plexiform neurofibromas, optic pathway gliomas ependymomas, meningiomas astrocytomas, and pheochromocytomas. Neurofibromas may undergo secondary malignant degeneration and become sarcomatous. |
NF2 is characterized by the
development of bilateral vestibular schwannomas in >90% of individuals who inherit the gene Patients with NF2 also have a predisposition for the development of meningiomas, gliomas, and schwannomas of cranial and spinal nerves |
Exam Important
- Neurofibromatosis shows which of the Autosomal Dominant type of inheritance.
- Neurofibromatosis may be associated with Cataract, Scoliosis, Hypertrophy of limb and Neurofibroma.
- Neurofibromatosis-1 is asociated with family history, Optic Glioma and Axillary Freckles.
- Optic Gliomas are the most common intracranial tumors of Neurofibromatosis 1.
- Neurofibromatosis type 2 is associated with Bilateral Acoustic Neuroma, Cafe-au-lait spots, Axillary Freckling, Lisch Nodule, Meningioma
- Gene for NF-2 is located on chromosome 22.
- Neurofibroma are unencapsulated and needs to be resected along the nerve fibres.
- Neurofibromatosis presents as Elephantiasis neuromatodes, Plexiform neuroma,Von Recklinghausen’s disease.
- Plexiform neurofibromatosis commonly affects Trigeminal Nerve.
- Neurofibromatosis may be associated with Pheochromocytoma.
- The pathognomic sign of Neurofibromatosis is Axillary Freckling.
- Scoliosisis is the MOST common skeletal manifestation in Type-1 Neurofibromatosis.
- Juveile Myelomonocytic Leukemia is the most common tumour associated with Neurofibromatosis -1 (NF-I) in a child.
- Rib notching,Pseudarthrosis may be seen in Neurofibromatosis.
- Wide neural foramina is associated with Neurofibromatosis.-I.
- Ependymomas are commonly associated with Neurofibromatosis-II.
- A 22-year-old patient, Sreeraj presents with multiple neural tumors, pigmented iris hamartomas, and numerous tan macules on his skin. He informs the physician that his father, as well as one uncle and his paternal grandfather, had a similar condition. This patient likely suffers from Neurofibromatosis.-I.
