Light micrograph section through human tissue showing a neurofibroma. This is a type of nerve tumour that forms soft bumps on or under the skin. It can develop within a major or minor nerve anywhere in the body. It's a common type of benign tumour that sometimes arises from several nerve bundles (plexiform neurofibroma). Symptoms of a neurofibroma are often mild or absent. Although usually non-cancerous, they rarely become malignant.