Light micrograph of a section through a neurofibroma, a tumor of the protective sheaths of nerves. The tumor 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 tumor can usually be removed surgically, but the original function of the nerve is often lost.