Dermatofibromas are benign tumors of fibroblast and histiocytic origins in the dermis, often referred to as benign fibrous histiocytomas that can happen after trauma.
Cause and Risk factors
They are neither hereditary nor cancerous. They most often appear after a minor injury/trauma to the skin such as a (prick from a thorn or an insect bite) but often with unknown cause.
Some cases of dermatofibroma may be associated with immune suppression such as lupus (SLE), Human immunodeficiency virus (HIV), some cancer like leukemia.
Symptoms and Clinical Presentation
Dermatofibromas present as firm papules or plaques with a dusky (dark) red to brown color, typically 0.3 to 1 cm in diameter but can also present with lesions > 3 cm. These lesion are usually asymptomatic but occasionally can be pruritic or irritated. They are most commonly found on the lower extremities.
Dermatofibroma retracts on palpation because they are fixed to the subcutaneous tissues and characteristically dimple after being pinched by examining doctor.
- Pinch test positive (giving dimple sign on pinching the sides).
- Diagnosed clinically but if in doubt, biopsy can be performed under local anesthesia.
Treatment of Dermatofibroma
Dermatofibroma can disappear spontaneously and therefore not treated unless symptomatic. They may require treatment when there is bleeding, enlarging in size or suspicion for malignancy. However, most treatment are for cosmetic reasons. Therapy involves intralesional corticosteroids with limited results, Cryotherapy, Simple surgical excision.