Abstract:

One of the common challenges encountered by dermatopathologists is differentiation of dermatofibroma (DF) from dermatofibrosarcoma protuberans (DFSP) based on partial sampling. Studies which correlate the histopathologic characteristics of partial biopsies of DF and DFSP with definitive features of excisional specimens are lacking. The aim of this project is to provide real world utility by identifying helpful morphological features of partial biopsy specimens of DF and DFSP. A retrospective review was conducted to identify subjects with diagnosis of DF or DFSP. Inclusion criteria for partial biopsy consisted of shave, incisional, or punch biopsies, with or without subcutis; for excisional specimens, excisions with wide margins or excisional biopsies with subcutis were included. This study included 8 DFs, 22 Cellular DFs, and 6 DFSPs. The morphologic features examined included epidermal induction, presence of a grenz zone, peripheral collagen trapping, chronic inflammatory infiltrate, hemosiderin, floret-like giant cells, fat necrosis with lymphocytic infiltrate, and cellular pleomorphism. As expected, DFs and Cellular DFs, demonstrated increased incidence of peripheral collagen trapping when compared to DFSPs and this was present in both superficial biopsied as well as excision specimens. Interestingly, the presence of floret-like giant cells, chronic inflammatory infiltrate, cellular pleomorphism, and fat necrosis with lymphocytic infiltrate was increased in DF and Cellular DF biopsies and excisions compared to DFSPs. Cellular pleomorphism was most prominent in cellular DFs. Unfortunately, given the limited sample size of this study none of these trends reached statistical significance. However, this data does support larger studies further investigating the morphologic differences between partial biopsies of DF and DFSPs with specific focus on the features mentioned above.

Financial Disclosure:
No current or relevant financial relationships exist.

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Nathan Bowers, MD, PhD