What is dermatofibroma (DF)?

Updated: Oct 07, 2019
  • Author: Guy J Petruzzelli, MD, PhD, MBA, FACS; Chief Editor: Gregory Gary Caputy, MD, PhD, FICS  more...
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Dermatofibromas (DFs) are common benign cutaneous tumors. Of unknown etiology, DFs usually occur as solitary lesions on the extremities; however, they may appear as multiple nodules. The presence of multiple nodules (>15) can be indicative of lupus or human immunodeficiency virus (HIV). Evidence found of clonal growth within the lesion suggests that DFs are true neoplastic growths rather than the result of reactive processes. [77]  

DF can be diagnosed clinically with the Fitzpatrick sign, also called the dimple sign, in which lateral pressure against the tumor produces a depression. The presence of factor XIIIa within cells is thought to indicate a DF rather than a dermatofibrosarcoma protuberans (DFSP). The presence of CD34, on the other hand, is positive in DFSP and not DF. However, these immunostains are not infallible. 

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