The precise mechanism for the development of DF is unknown. Rather than a reactive tissue change, DF seems more likely to be a neoplastic process due to the persistent nature of the lesion. Immunohistochemical testing with antibodies to factor XIIIa is frequently positive in DF, while antibodies to MAC 387 show less consistent results. Such reported lesions were highly cellular, of large size and locally recurrent. Indolent pulmonary metastases were also observed.
Frequency appears to be similar in all races.
Dermatofibromas typically arise slowly and most often occur as a solitary nodule on an extremity, particularly the lower leg, but any cutaneous site is possible. This multiple variant is seen most frequently in the setting of autoimmune disease or altered immunity such as systemic lupus erythematosus or HIV infection. Dermatofibromas are characteristically asymptomatic, but itching and pain are often noted. They are the most common of all painful skin tumors. Women who shave their legs may be bothered by their razor traumatizing the lesion in that region, causing pain, bleeding, and ulceration.