What is a dermatofibroma?
A dermatofibroma is a common benign fibrous nodule that most often arises on the skin of the lower legs.
A dermatofibroma is also called a cutaneous fibrous histiocytoma.
Who gets dermatofibroma?
- Dermatofibromas occur at all ages and in people of every ethnicity. They are more common in women than in men.
What causes dermatofibroma?
It is not clear if dermatofibroma is a reactive process or if it is a neoplasm. The lesions are made up of a proliferation of fibroblasts. Histiocytes may also be involved.
They are sometimes attributed to an insect bite or rose thorn injury, but not consistently. They may be more numerous in patients with altered immunity.
What are the clinical features of dermatofibroma?
Dermatofibromas most often occur on the legs and arms, but may also arise on trunk or any site of the body
- People may have 1 or up to 15 lesions.
- Size varies from 0.5–1.5 cm diameter; most lesions are 7–10 mm diameter.
- They are firm nodules tethered to the skin surface and mobile over subcutaneous tissue.
- The skin dimples on pinching the lesion.
- Colour may be pink to light brown in white skin, and dark brown to black in dark skin; some appear paler in the centre.
- They do not usually cause symptoms, but they are sometimes painful or itchy.
Complications of dermatofibroma
Because they are often raised lesions, they may be traumatised, for example by a razor.
Occasionally dozens may erupt within a few months, usually in the setting of immunosuppression (for example autoimmune disease, cancer or certain medications).
Dermatofibroma does not give rise to cancer. However, occasionally, it may be mistaken for dermatofibrosarcoma or desmoplastic melanoma.
How is dermatofibroma diagnosed?
Dermatofibroma is usually easy to diagnose clinically, supported by dermatoscopy. The most common dermatoscopic pattern is a central white area surrounded by faint pigment network.
The histology shows whirling fascicles of spindle cell proliferation with excessive collage deposition in the dermis. There are several pathological variants of dermatofibroma.
- lipidized ankle-type
In case of doubt, immunohistochemical staining is used to confirm the diagnosis.
What is the treatment for dermatofibroma?
A dermatofibroma is harmless and seldom causes any symptoms. Usually only reassurance is needed. If it is nuisance or causing concern, the lesion can be removed surgically.