Solitary tumours of peripheral nerve trunks.

Primary solitary tumours of the peripheral nerve trunks are relatively infrequent. Three such tumours have been treated at Hammersmith Hospital during the last four years, but a search of the hospital records for the period 1939-1950 has not shown any similar cases. (Solitary tumours of the auditory nerve and spinal nerve roots are not included in this report.) In these three patients the tumour involved the radial, lateral popliteal and ulnar nerves respectively. In only one of them was the diagnosis made before operation. A swelling arising from a main nerve trunk may be a traumatic false neuroma, a neurofibroma, a neurilemmoma or, more seldom, a neurofibrosarcoma. There are only two benign tumours which arise from nerve trunks. One of these is the neurilemmoma, which develops from the cells of Schwann, and with which this paper is mainly concerned; the other is the neurofibroma, which is derived from fibroblasts and will be discussed only in relation to the true neurilemmoma. Nerve axons cannot give rise to tumours independently of their parent cells, but if damaged or divided they coil up into a mass of connective tissue and give rise to a false neuroma. Peripheral tumours of nerve cells can occur only in situations where there are nerve ganglia, as in the sympathetic plexuses or the thoracic root ganglia. They are included in the group of ganglion-neuromas, comprising less than one per cent of nerve tumours outside the central nervous system, and will not be discussed here.