Dermatofibroma: what it is, treatment and removal

BAD says dermatofibromas are harmless, so treatment is not usually necessary other than an accurate diagnosis and reassurance. PCDS says most dermatofibromas persist and that treatment is not often available on the NHS. Newcastle Hospitals NHS Foundation Trust says the only possible treatment is surgery, which leaves a scar, so they are usually best left alone.

BAD lists three situations in which treatment may be appropriate: there is any doubt about the diagnosis, the lesion is unsightly (although a scar will be in its place), or it is causing symptoms such as itching or pain. It notes that these symptoms may stop with time, and that the scar after removal may also be itchy or painful.

The exact cause is not clear. BAD and PCDS both say they often seem to appear after a minor injury to the skin such as an insect bite, with BAD adding a prick from a thorn. They are more common in females than males, for reasons BAD says are not known. BAD says there is no evidence to suggest dermatofibromas are hereditary.

Most people have only one. BAD says that, rarely, some people develop several in a short time, which can be due to underlying immunosuppression caused by medication or diseases such as lupus, HIV and, rarely, certain cancers. If in doubt, seek medical advice.

BAD describes a dermatofibroma as a common overgrowth of the fibrous tissue in the dermis, the deeper of the two main layers of the skin. PCDS, which writes for GPs, describes it as a common type of fibrous or scarring reaction in the deeper layer of the skin and says it is also known as a histiocytoma.

Both say it is benign. Even so, BAD points out that dermatofibromas can be similar in appearance to other concerning skin tumours, so it is important to see a health professional for a diagnosis.

BAD describes a firm bump that feels like a small rubbery button lying just under the surface of the skin, seldom larger than 1 cm in diameter. They can vary in colour from purple to pink and can sometimes appear brown or grey. A dimple may appear over a dermatofibroma when pinched.

PCDS says they can appear anywhere but are most common on the lower legs of young to middle-aged adults, and on the upper arms in females. Most appear as a symmetrical, smooth raised bump, and occasionally they are flat. On white skin they are most commonly pink to skin-coloured in the centre with a slightly brown edge, while on skin of colour they tend to be brown or black.

Usually there are no symptoms, but some people are concerned about the appearance, according to BAD. Occasionally a dermatofibroma can itch or become painful when touched or knocked. If one is on the leg, shaving the skin over it can cause bleeding, as BAD and PCDS note.

BAD says a doctor can usually identify a dermatofibroma easily by its appearance. PCDS says a healthcare professional may diagnose one by examining you, sometimes with a dermatoscope, a small hand-held instrument that allows a much more detailed examination.

If the diagnosis is uncertain, PCDS says you may be referred to a dermatologist or a GP with extended training in dermatology, and increasingly the first referral may be through teledermoscopy, where a picture of the lesion is sent to a specialist for advice. Occasionally a small skin biopsy under local anaesthetic is needed to confirm the diagnosis. BAD says that if there is doubt about the diagnosis or concern about skin cancer, the lesion can be removed under local anaesthetic and looked at under a microscope.

BAD advises that anyone who develops a new lump on their skin, particularly if it is pigmented, should seek the advice of their doctor or health professional for a formal diagnosis. PCDS stresses that it is very important to know how to examine your own skin and to understand what skin cancer looks like.

If a lump is changing, bleeding or worrying you, have a professional look at it rather than relying on home tests such as the pinch test.

The usual NHS route is a GP examination, with a dermatology or teledermoscopy opinion if there is doubt. BAD and PCDS both say removal of a harmless dermatofibroma is often not available on the NHS, so cosmetic removal commonly happens privately.

If you choose private removal, ask what scar to expect, whether the specimen will be sent for pathology (sensible whenever the diagnosis is not completely certain), what the chance of the lesion coming back is and what aftercare is included. Treat promises of scar-free removal with caution, given what the dermatology sources say about scarring.