• First described in 1924 by Darier and Ferrand
  • Intermediate-grade malignancy thought to arise from dermis
  • Appears clinically as a nodular cutaneous mass that may, with time, develop satellite nodules or even nodal/visceral metastases
  • Histologically similar to solitary fibrous histiocytoma, and can be confused with plexiform neurofibroma
    • DFSP distinguished from solitary fibrous histiocytoma by diffuse CD34 positivity, and from plexiform neurofibroma by a complete absence of S100 positivity
  • 95% of DFSPs characterized by t(17;22), which fuses PDGF-beta gene to the constitutively active Col1A1 promoter, leading to overproduction of PDGF-beta locally
    • Thought to be primarily responsible for observed phenotype
  • Primary treatment is wide surgical excision
  • Tyrosine kinase inhibitor imatinib active against PDGF-beta receptor-associated tyrosine kinase; has been shown to be effective adjuvant in recurrent disease
  • Can dedifferentiate, most commonly into a high-grade fibrosarcoma; secondary fibrosarcoma arising from DFSP typically does not express CD34
  • Pigmented variant known as a Bednar tumor

Reference

Enzinger and Weiss’s Soft Tissue Tumors. 4th ed. Mosby 2001.