The dermatoscope revealed a fine reticular network around a central scar, which confirmed a diagnosis of dermatofibroma. A dermatofibroma is a benign fibrohistiocytic tumor found in the mid dermis, composed of a mixture of fibroblastic and histiocytic cells. It represents a fibrous reaction triggered by trauma, a viral infection, or an insect bite. Many dermatofibromas have a hyperpigmented halo around a central hypopigmented fibrous scar.
Dermoscopy is a very useful diagnostic technique for dermatofibroma. The most common pattern found is a peripheral reticular pigment network with a central hypopigmented stellate area.
No treatment is necessary unless the diagnosis is uncertain or symptoms warrant it. Dermatofibromas can be removed using punch excision for small lesions or an elliptical (fusiform) excision down to the subcutaneous fat for larger lesions. Cryotherapy is one option to shrink the lesion, but the cure rate is low and lesions may regrow.
The patient was relieved that the lesion was not cancer and opted to leave it be, as it was not bothering him.
Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Smith M. Usatine R. Dermatofibroma. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. Color Atlas of Family Medicine. 2nd ed. New York, NY: McGraw-Hill; 2013: 935-939.
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