Solitary neurofibroma

What is a solitary cutaneous neurofibroma?

A solitary cutaneous neurofibroma is a common nerve-sheath tumour. It presents as a skin-coloured, soft-to-firm papule or nodule with a smooth surface. Characteristically, pressing on the lesion with a finger causes it to fold in so that the outer surface becomes an inner one, a manoeuvre called "buttonhole invagination".

Solitary neurofibroma

Solitary neurofibroma

Solitary neurofibroma

Who gets solitary neurofibroma?

Neurofibroma is usually diagnosed in young adults. As neurofibromas persist, they may also be diagnosed in older or younger people. It is equally prevalent in both sexes.

Solitary neurofibroma must be distinguished from the genetic disorder neurofibromatosis, in which there are multiple neurofibromas, café-au-lait macules, and other features.

What are the risk factors for solitary neurofibroma? 

No definitive risk factors have been identified for solitary neurofibroma, which is not inherited.

What is the cause of solitary neurofibroma?

The cause of solitary neurofibroma is unknown.

What are the clinical features of a solitary neurofibroma?

Solitary neurofibroma usually arises in second or third decade of life and will be located on the skin of the head and neck, trunk or proximal limbs. Characteristics are:

• A soft, flaccid or rubbery, dermal or subcutaneous, asymptomatic papule or nodule
• A pedunculated lesion arising from under the skin surface
• 2–20 mm in diameter
• Pinkish-white to dark brown — usually similar to the normal skin colour.

How is solitary neurofibroma diagnosed?

The diagnosis of solitary neurofibroma may be suspected from its typical clinical features, in the absence of significant signs and symptoms of neurofibromatosis. A neurofibroma is featureless on dermoscopy, distinguishing it from a smooth-surfaced dermal naevus, (which usually shows some areas of pigmentation).

Note that a solitary plexiform neurofibroma, which mostly presents as a bag-like mass on the trunk or proximal extremities, is pathognomonic for neurofibromatosis type 1.

Skin biopsy may be undertaken; the pathology of neurofibroma is diagnostic.

What are the possible complications of neurofibroma?

Unlike neurofibromatosis, any concern about solitary neurofibroma is purely cosmetic.

What is the treatment for solitary neurofibroma?

Solitary neurofibroma is a benign tumour and rarely requires any treatment. If there is discomfort, diagnostic uncertainty, or cosmetic concern, it can be surgically excised.