This is a form of congenital ectodermal abnormality due to hyperplasia of the connective tissue supporting the nerves. The disease may occur either sporadically or on a familial basis. There are two types-Type I and Type II. Type I is generalized neurofibromatosis and Type II is localised type. In the familial cases the gene for type I is located on chromosome 17 and in Type II it is located at chromosome 22.
Age 20-40 years.
Type I — Generalised neurofibromatosis.
(von Recklinghausen’s disease)
This occurs as an autosomal dominant trait. In this condition multiple tumours arise from the peripheral cutaneous nerves and may project as small nodules in all or some parts of the body. Skin may show hyperpigmentation (Café-au-lait spots) particularly on the trunk. This type of patch is seen in normal individuals also. But when more than 6 such patches are seen with smooth periphery 1.5 cm in diameter, it is said to be abnormal. Axillary frenkles may be seen with hyperpigmented skin change and is known as Crowe’s sign.
Small pinkish cutaneous fibromas which may be sessile or pedunculated (Molluscum fibrosum) may be found on the trunk and face and sometimes overgrowth of subcutaneous tissue particularly on the forehead, upper eyelid and neck may also be seen (plexiform neuroma). Oral lesions may also develop. Local gigantism of limb may follow. All these constitute elephantiasis with neuro-fibromatosis.
Associated bony abnormalities like spina bifida, kyphoscoliosis, spondylolisthesis, subperiosteal hyperostosis, bone cyst, etc. are present.
Sometimes other tumours or lesion may be associated, e.g., glioma, meningioma-obstructive hydrocephalus, haemangioma, phoeochromocytoma, renal artery stenosis, fibrous dysplasia of bones, obstructive cardiomyopathy, pulmonary fibrosis, etc. Malignant degeneration may occur leading to sarcoma.
Type II- Localised neurofibromata.
Auditory or Less commonly facial nerve tumour
This usually arises at the cerebellopontine angel. Effects are described in Facial Nerve.
Peripheral nerve tumour
Radial nerve tumour is seen when it pierces the lateral intermuscular septum, median nerve tumour is seen where it passes behind the tendinous bridge joining the origins of flexor digitorum sublimis and also ulnar nerve tumour is seen where it passes into the hand. Effect will vary accordingly.
Spinal nerve root tumour or
These arise from the intervetebral foramina and therefore, part of the tumour is inside the spinal canal and the remaining part in the thorax or abdomen. This may cause spinal cord compression.
Localised neurofibromata may be excised surgically or treated by deep X-ray therapy. For other varieties, treatment is essentially palliative. Plastic surgery may be required.