Updated: 6/22/2021

Dermatofibrosarcoma Protuberans

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  • summary
    • Dermatofibrosarcoma Protuberans are rare, low-grade fibrogenic cutaneous sarcomas that occur in early to mid-adult life.
    • Diagnosis is made with a biopsy showing uniform fibroblasts arranged in storiform pattern around an inconspicuous vasculature.
    • Treatment is usually wide surgical resection with radiation therapy.
  • Epidemiology
    • Incidence
      • accounts for 1% of soft tissue sarcomas
    • Demographics
      • slightly more common in males
      • usually presents in people aged 20-50 years old
      • more common in African Americans (2:1) vs. Caucasians
    • Anatomic location
      • trunk > proximal extremities > head/neck
  • Etiology
    • Variants 
      • Bednar tumor 
        • pigmented variant that is 7.5x more common in African Americans
      • fibrosarcomatous
        • more aggressive variant with poor prognosis
    • Genetics
      • mutations
        • associated with t(17;22)
          • encodes for PDGF-beta chain (PDGFB)/collagen type I alpha 1 (COL1A1) fusion protein
  • Symptoms
    • Presentation
      • usually an slowly enlarging painless mass
        • composed of firm irregular nodules
        • may have dark red or blue discoloration
  • Imaging
    • Radiographs
      • views
        • CXR
      • indications
        • screen for pulmonary metastasis in high-risk cases (i.e. recurrence or suspicion for a fibrosarcoma variant of DFSP)
    • CT
      • indications
        • suspected direct bone involvement or metastasis
    • MRI
      • indications
        • preoperative assessment in larger or atypical lesions and recurrent disease
    • Ultrasound
      • indications
        • monitoring of local DFSP or regional lymph node metastasis
    • PET
      • indications
        • monitoring of metastatic disease
  • Histology
    • Biopsy is required for diagnosis
    • Histology
      • classically appears as uniform fibroblasts arranged in storiform pattern around an inconspicuous vasculature
      • Bednar variant has scattered melanin-containing dendritic cells
      • fibrosarcomatous variant has a characteristic herringbone pattern
  • Treatment
    • Nonoperative
      • imatinib
        • inhibits PDGF-receptor tyrosine kinase
        • indications
          • adult patients with unresectable, recurrent, and/or metastatic DFSP
        • outcomes
          • 65% response rate
          • no response in patients who lack the t(17,22) mutation
    • Operative
      • wide surgical resection +/- adjuvant radiation therapy
        • indications
          • patients with resectable DFSP
          • adjuvant radiation therapy is useful in patients with positive margins or in whom adequate wide excision alone may result in major cosmetic or functional deficits
        • technique
          • clean margins are an important goal of surgical resection
            • obtain 2-3cm margins
            • dissect deep to and excise all tissue including the fascia
          • total dose of radiation therapy is 50-70 Gy
        • outcomes
          • 15.7% recurrence for lesions on the body
          • 51.8% recurrence rate for lesions on the head/neck
    • Location
      Xray
      Xray
      CT
      B. Scan
      MRI
      MRI
      Histo(1)

      Case A

      tibia
  • Prognosis
    • Local recurrence is common
    • Distant metastasis is rare (< 5%)
      • lung is the most common site of distant metastasis
      • occurs via hematogenous spread
      • usually preceded by multiple local recurrences
    • Worse prognosis seen with
      • regional lymph node involvement
      • fibrosarcomatous progression DFSP variant
      • histologic features: high number of mitotic figures, increased cellularity, DNA aneuploidy, TP53 gene overexpression, and the presence of fibrosarcomatous changes
      • age > 50 years old

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