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

What is a Dermatofibroma?

Dermatofibroma is a common, harmless &  benign growth. Dermatofibroma is four times more common in females than males, and occurs more commonly in young adults. They usually develop between the ages of 20 and 50. The most common site is the calf but they  occur in many different parts of the body.

The growth often persist for years. Indeed, they are commonly seen at a skin check and most people say they have had them “a long time.”

A harmless old wives tale says that the lesion occurs a reaction to trauma such as an insect bite or inflamed hair follicle. In truth, the cause is not known. 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 called “eruptive dermatofibroma” and occurs in under 1% of cases. Causes of the eruptive type include immune-mediated diseases.

What does a Dermatofibroma look like?

The lesion projects upwards from the skin surface. The colours of dermatofibroma vary. The classical dermatofibroma has a pink or flesh coloured centre with a pale brown surround. 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”).