A dermatofibroma is a common, harmless growth of fibrous tissue in the dermis, most often on the legs of young and middle-aged adults. It may follow a minor injury such as an insect bite and usually stays the same size for years.
Key symptoms
- Small firm bump, usually on the lower leg
- Pink, tan or brown color
- Usually no symptoms; sometimes mild itch or tenderness
- Can catch on a razor when shaving
What you find on exam
- Firm papule or nodule 0.5 to 1 cm across that feels like a button in the skin
- Dimple sign: the lesion sinks inward when the skin on both sides is pinched
- Dermoscopy: central white patch with a fine brown network around it
- Compare with other lesions and check for warning features of melanoma
Tests
- Usually a clinical diagnosis
- Biopsy if the lesion is growing, larger than 2 cm, irregular or atypical
- Biopsy if it bleeds, ulcerates or does not show the dimple sign
Treatment basics
- Reassurance; no treatment is needed
- Surgical excision if symptomatic, if the diagnosis is uncertain or for cosmetic reasons
- Explain that excision leaves a scar and the lesion can return if not fully removed
Red flags
- Rapid growth or size over 2 cm
- Irregular color, bleeding or ulceration
- Lesion fixed to deeper tissue (consider dermatofibrosarcoma protuberans)
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.