Neurofibroma
Author: Gaelle Salameh
Chief Editor: Dr Daniel Keith
A neurofibroma is a benign tumor that develops from the nerve sheath and can occur sporadically or in people with neurofibromatosis type 1. Although these tumours are typically asymptomatic, they can sometimes lead to pain and disfigurement in those with neurofibromatosis type 1 (NF1).
Neurofibromas can be difficult to diagnose, especially if they appear as solitary lesions. NF1 is a useful condition to get your eye in for diagnosing Neurofibromas because they'll be covered in thousands. However, it's the solitary ones that catch people out and get mistaken for BCC and referred. There's no difference in the tumours themselves between NF1 and solitary neurofibromas.
Differential diagnosis include benign and malignant skin tumours, like intradermal naevi, dermatofibroma, trichoepithelioma, skin tag (acrochordon), pedunculated encapsulated neuroma, schwannoma, leiomyoma, and basal cell carcinomas.
Macroscopic Appearance
Neurofibromas present as painless, sessile or pedunculated, slow-growing, soft to firm papule or nodule with a smooth surface. They can vary in size, reaching up to 2 cm, and the colour can vary from skin colour to dark brown (including shades such as yellow, yellow-brown, brown, and dark brown).
The buttonhole sign is often positive; this sign indicates that the tumour can be pushed into the underlying skin with gentle pressure, creating the sensation of inserting a finger into a buttonhole (NB this sign can be also found in several other conditions).
A solitary neurofibroma on the nose.
Image courtesy of Dr. Luke Parker, GP.
Another solitary neurofibroma on the nose.
Multiple neurofibromas in a patient with neurofibromatosis type 1.
Dermoscopic Appearance
The dermoscopic characteristics of neurofibroma were not well understood until recently, when several findings were identified.
Dermoscopy shows a circular delimited lesion with a white scar-like patch in the middle and a pigmented halo on the edges. Fingerprint‑like pigmentary lines and peripheral pigment network were also noted.
Please note that vascular structures are generally not found in neurofibromas. However, some of our images do display telangiectasia. While this is not typical for neurofibromas, it can occur in cases of recurrent trauma, particularly in areas that experience frequent impact or irritation, such as the nose.
Figure 1-2-3-4 annotations:
-
Red star: peripheral pigment network: regular or irregular brown network extending the borders of the lesion
-
Orange star: peripheral halo of hyperpigmentation: continuous or discontinuous dark or light brown homogeneous pigmentation at the borders
-
Green star: fingerprint-like pigmentary lines: brown, fine, parallel cord-like structures
-
Pink star: pink-red structureless areas
-
Blue star: central white scar like area
Figure 1
Dermoscopic example (annotated)
-
Red star: peripheral pigment network
-
Orange star: peripheral halo of hyperpigmentation
-
Green star: fingerprint-like pigmentary lines
-
Pink star: pink-red structureless areas
-
Blue star: central white scar like area
Figure 2 (a)
Dermoscopic example (unannotated)
Figure 2 (b)
Dermoscopic example (annotated)
-
Orange star: peripheral halo of hyperpigmentation
-
Green star: fingerprint-like pigmentary lines
-
Pink star: pink-red structureless areas
Figure 3 (a)
Dermoscopic example (unannotated)
Figure 4 (a)
Dermoscopic example (unannotated)
Figure 3 (b)
Dermoscopic example (annotated)
-
Pink star: pink-red structureless areas
-
Blue star: central white scar like area
Figure 4 (b)
Dermoscopic example (annotated)
-
Red star: peripheral pigment network
-
Green star: fingerprint-like pigmentary lines
-
Pink star: pink-red structureless areas
-
Blue star: central white scar like area
Below is a further example of a neurofibroma on the shoulder of a patient. You can see the macroscopic (left) and dermoscopic (right x2) for direct comparison. This patient is a roofer who carried his ladder on that shoulder hence the telangiectasia from trauma.
Figure 5a (macroscopic)
Figure 5b (dermoscopic unannotated)
Figure 5c (dermoscopic annotated)
-
Red star: peripheral pigment network
-
Orange star: peripheral halo of hyperpigmentation
-
Green star: fingerprint-like pigmentary lines
-
Pink star: pink-red structureless areas