Neurofibroma tumour. Light micrograph of a section through a neurofibroma, a tumour of the protective sheaths of nerves. The tumour is slow-growing and benign (non-cancerous), but its growth puts pressure on the affected nerves. Symptoms depend on the location of the affected nerve. If it supplies an extremity it may cause tingling or paralysis. A type of neurofibroma called an acoustic neuroma affects the ear, and may cause tinnitus (ringing), deafness and balance problems. The tumour can usually be removed surgically, but the original function of the nerve is often lost.