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Background Dermatofibrosarcoma protuberans (DFSP) is an uncommon cutaneous tumor, usually low grade, except for the fibrosarcomatous variant (DFSP-FS). Objectives We sought to compare the clinicopathological, immunohistochemical, genetic, and therapeutic features between DFSP and DFSP-FS. Methods The clinicopathological features were reviewed in 63 DFSP and 12 DFSP-FS. Immunohistochemistry and multiplex reverse transcriptase-polymerase chain reaction were carried out using formalin-fixed, paraffin-embedded tissue, using specific primers for collagen type I alpha 1 ( COL1A1 ) and platelet-derived growth factor beta ( PDGFB ). Results DFSP-FS was associated with tumor history longer than 5 years ( P = .009), tumor size greater than 4 cm ( P = .001), more stages of modified Mohs micrographic surgery ( P = .005), expansive subcutaneous infiltration ( P = .005), muscular invasion ( P = .0001), absence of CD34 staining ( P = .018), p53 positivity ( P = .006), and increased proliferative activity ( P = .004) compared with DFSP. The COL1A1-PDGFB fusion transcript was found in 100% DFSP-FS and 72% DFSP. No association was found between the different COL1A1-PDGFB fusion transcripts and the different histologic subtypes. Wide local excision (2 cm) was performed in 47% of cases and modified Mohs micrographic surgery in 53%. After a mean follow-up of 73 months (range 21-235), 6 patients had local recurrence (5 DFSP, 1 DFSP-FS) and one died of disease (DFSP-FS). The only factor related to local recurrence was the type of surgery (17% wide local excision vs 0% modified Mohs micrographic surgery) ( P = .006). Limitations Our study is retrospective. Prospective studies are necessary to confirm our results. Conclusions DFSP-FS reflects tumor progression in DFSP, with larger size, particular invasive patterns, p53 expression, and increased proliferative activity. However, as in low-grade DFSP, appropriate surgery permits a tumor-free excision. COL1A1-PDGFB is a useful tool for diagnosis of DFSP and particularly for DFSP-FS. |
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