Clinicopathologic Comparison of Dermatofibroma and Dermatofibrosarcoma Protuberans

Song, Byong Han; Park, Eun Joo; Kwon, In Ho; Kim, Kwang Ho; Kim, Kwang Joong

Abstract

BACKGROUND
The histologic distinction of dermatofibrosarcoma protuberans (DFSP) and dermatofibroma (DF) may be difficult, especially in the case of DF extending into the subcutaneous fat. CD34 and Factor XIIIa stains are commonly used in distinguishing the DF from DFSP, but is not always helpful. There are no studies regarding the clinicopathologic comparison of DF and DFSP.
OBJECTIVE
The aim of our study was to evaluate the clinicopathologic characteristics and differences between the DF and DFSP.
METHODS
Retrospective analysis was performed by reviewing the clinicopatholgic records of 40 patients who were diagnosed with DF, and 11 patients who were diagnosed with DFSP, from 1998 to 2012 in Hallym University Medical Center.
RESULTS
The ratio of male to female patients in DF and DFSP were 1:2.1 and 1:1.8, respectively. Disease onset ages were 32.6 years and 34.4 years, respectively. The average size was 0.8 cm and 2.0 cm, respectively. The most frequent location was the lower extremity and the trunk, respectively. No symptom was most common subjective symptom in both DF and DFSP. Most of DF presented as brown colored papules and the lesions of DFSP were reported mainly as brown plaques. Histopathologically, the 40 cases of DF were classified as 24 fibrous types, 12 cellular types and 4 aneurysmal types. Of the 11 DFSP, two cases were classified as myxoid type, one case as pigmented lesion (Bednar tumors) and one case as fibrosarcomatous type. Histopathologic findings of the DF showed more significant epidermal hyperplasia, basal hyperpigmentation and collagen trapping, compared to that of the DFSP. The subcutaneous extension and honeycomb pattern were significantly more present in DFSP than in DF. The immunoreactivity of CD34 in DFSP was generally strong and diffuse, in contrast to absent or focal staining seen in DF.
CONCLUSION
We conclude that several cilinicopathologic features, including size, location, epidermal and tumoral component, and immunostaining, for CD34 can be used to distinguish DF from DFSP. Further research regarding the characteristics and differences between DF and DFSP should be performed on larger number of cases.