| neurofibroma | <oncology, tumour> A neurofibroma is a smooth, polypoid, soft or firm tumour that arises from the Schwann cells and fibroblasts of the neurilemmal sheath. They may grow anywhere in the myelinated nervous system. (27 Sep 1997) |
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| neurofibroma, plexiform | A type of neurofibroma representing an anomaly rather than a true neoplasm, in which the proliferation of schwann cells occurs from the inner aspect of the nerve sheath, thereby resulting in an irregularly thickened, distorted, tortuous structure. In some instances the process extends along the course of the nerve and may eventually involve the spinal roots and the spinal cord. (12 Dec 1998) |
| neurofibromatosis | <oncology> One of the most common disorders in genetics, neurofibromatosis encompasses at least two diseases, designated NF-1 and NF-2. NF-1 or classic neurofibromatosis, is characterised by the familiar cafe- au-lait spots, axillary freckling, cutaneous and visceral neurofibromas (which sometimes undergo malignant transformation), gliomas, scoliosis, and Lisch nodules of the iris. NF-1 is associated with the the von Recklinghausen Neurofibromatosis locus that encodes the NF-1 protein, a GTPase activating protein which interacts with the ras proteins. The gene is located on chromosome 17. NF-2, also called acoustic or central neurofibromatosis, features neurofibromas restricted to the acoustic nerve (usually bilateral) and the central nervous system, skin lesions may or may not be present. The gene is located on chromosome 22. There are no biochemical markers of the disorder, but the cloning of both the NF-1 and NF-2 genes makes DNA-based diagnosis possible in some families. Both genes appear to be tumour suppressor genes. Both conditions are autosomal dominant, but the variable penetrance and expressivity and high frequency of new mutations make genetic counseling difficult. Inheritance: autosomal dominant. (29 Dec 1997) |
| neurofibromatosis 1 | A congenital autosomal dominant disorder characterised by developmental changes in the nervous system, muscles, bones, and skin especially in those derived from the embryonic neural crest. There are multiple cutaneous tumours and tumours of the peripheral and central nervous system. The disease has been linked to mutations of the nf1 gene on chromosome 17. (12 Dec 1998) |
| neurofibromatosis 2 | Severe autosomal dominant disorder characterised especially by bilateral acoustic neuromas as well as other multiple tumours including meningiomas, ependymomas, spinal neurofibromas, and gliomas. The disease has been linked to mutations of the nf2 gene on chromosome 22. (12 Dec 1998) |
| storiform neurofibroma | An uncommon variant of dermatofibrosarcoma protuberans containing heavily pigmented dendritic melanocytes scattered between spindle cells of the tumour. Synonym: Bednar tumour, storiform neurofibroma. (05 Mar 2000) |
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