Neurofibromatosis

Eight subtypes of the disease have been identified, although only two subtypes (neurofibromatosis-1 and neurofibromatosis-2) account for 99% of cases. Neurofibromatosis-1 is also known as von Recklinghausen's disease.

Caf au lait spots and the lesions of molluscum fibrosum are common. Another typical manifestation is a lesion of the iris termed the Lisch nodule. These nodules may be neurofibromas arising from peripheral schwannian elements or melanocytic hamartomas of neural crest origin.

Bone abnormalities involve the cranium, spine and other sites. Scoliosis (with or without kyphosis) may lead to either an ordinary spinal curve or a dysplastic, sharply angulated, short segment kyphoscoliosis frequently involving fewer than six middle or lower thoracic vertebrae. Other spinal abnormalities include vertebral body wedging and scalloping, pedicle erosion, foraminal enlargement, and pencilling and spindling of transverse processes and ribs. In other sites, bowing and pathologic fracture of long bones occur. After fractures, bones often fail to reunite, ultimately resulting in pseudarthrosis.

Abnormalities involving the spinal nerves include meningocoele and neurofibroma, which may be difficult to differentiate radiographically. Tumours of cranial nerves may be schwannomas, neurinomas, gliomas or meningiomas. Peripheral nerve tumours in neurofibromatosis most frequently involve neural supporting tissues and include solitary or multiple neurofibromas and neurilemomas (schwannomas (Fig. 1). In some cases malignant degeneration may occur. Occasionally rhabdomyosarcoma, liposarcoma or osteosarcoma may also occur in the soft tissues of patients with this disease.

Additional features are macrocranium, elephantiasis neuromatosa (soft tissue hypertrophy of an entire limb or part of a limb), massive or recurrent haemorrhage, cystic bone lesions (subperiosteal or intraosseous), and vascular, endocrine or pulmonary lesions.

DR/RB