Dermatofibroma is a harmless hard nodule that is often found on the legs.

What is a Dermatofibroma?

Dermatofibroma is simply known as DF,  and is a common, harmless &  benign growth. Dermatofibroma (DF) usually develops between the age of 20 and 50. The most common site is the leg. However, DF can  occur in many different parts of the body.

DF often persists for years. Indeed, DF is commonly seen at a skin check when the typical story is that the person knows they have ‘had it a long time.’

The cause of Dermatofibroma is not known. Doctors traditionally say that DF is a longstanding reaction to an insect bite. The pathology is that of a benign growth consisting of fibrous tissue which is similar tissue to that that found after an inflammatory reaction.

Dermatofibroma is usually solitary. More than 15 dermatofibromas is described as ‘eruptive dermatofibroma’ and occurs in under 1% of cases. Causes of eruptive DF include immune-mediated diseases.

What does a Dermatofibroma look like?

The lesion projects upwards from the skin surface in the shape of a dome. The colours of dermatofibroma vary. The classical DF has a pink or flesh- coloured centre with a pale brown periphery. Other colours are orange, yellow, red, or sometimes even purple, blue, or black. There may  be different colours in the same lesion. The size ranges from 3 to 10mm.

When squeezed between the finger and thumb, the hard nodule sinks below the skin (the “dimple sign”). This is really an important sign. Many people get confused by the dimple sign & palpate the skin too deeply. Just pinch the skin and you will certainly feel a very firm lesion.