Dermatofibroma is a common, benign skin lesion that often prompts concern when discovered. These growths are non-cancerous and medically harmless, typically presenting as small, firm nodules in the skin. Understanding the nature and course of a dermatofibroma is important for anyone who develops one.
What Dermatofibromas Are
A dermatofibroma, also known as a fibrous histiocytoma, is a firm nodule most commonly found on the lower legs or arms. They are typically reddish-brown to purple in color, though the exact shade can vary depending on the patient’s skin tone and the age of the lesion. A defining physical characteristic is the “dimple sign,” where pinching the lesion causes the overlying skin to retract slightly inward because it is tethered to the underlying tissue.
The exact cause is not fully established, but they often form as a reactive growth following minor local trauma. This trauma could be an insect bite, a superficial puncture wound, or even shaving. Histologically, the lesion consists of a localized proliferation of fibrous tissue, specifically fibroblasts and histiocytes, within the deeper layer of the skin known as the dermis. This dense internal structure explains why the nodules feel hard and persistent.
The Likelihood of Natural Regression
Complete, spontaneous resolution of a dermatofibroma is rare. Once the lesion has reached its full size, usually within a few months, it tends to remain static and persist indefinitely.
Although full disappearance is uncommon, some patients may observe subtle changes over many years, such as slight flattening or fading of the color. A small percentage of dermatofibromas may show some degree of involution or reduction in size over a very extended period. Even in cases of partial regression, the lesion typically leaves behind a mark, such as post-inflammatory hypopigmentation, rather than completely restoring the skin to its original state. The stability of the lesion is a reassuring feature, distinguishing it from growths that show continuous or rapid expansion.
Treatment and Management Strategies
Since dermatofibromas are benign and do not pose a health risk, observation is the most common management strategy. Treatment is usually only sought if the lesion causes persistent symptoms, such as pain or itchiness, or if the patient has significant cosmetic concerns. Intervention is also necessary if a doctor is uncertain of the diagnosis and needs to rule out other, more serious skin conditions.
When removal is elected, the gold standard for complete eradication is surgical excision. This method involves cutting out the entire lesion and closing the wound with stitches, providing the highest chance of full removal. Surgical excision will leave a permanent linear scar, which can sometimes be more noticeable than the original dermatofibroma.
Less invasive methods like shave excision or cryotherapy (freezing) may be used to flatten the lesion or reduce its prominence. However, these techniques often leave behind deeper fibrous tissue, leading to a higher risk of incomplete removal and local recurrence compared to full excision. Patients must weigh the desire for a less noticeable procedure against the possibility of the lesion growing back.