Pathology: dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans

  • Cellular; circumscribed; spindle cells with storiform pattern

  • Pale eosinophilic cytoplasm

  • Monomorphic ovoid nuclei; occasional mitotic activity

  • IHC: CD34

  • RNA-seq: COL1A1-PDGFB gene fusion

Dermatofibrosarcoma protuberans

  • Infiltrative; spindle-stellate cells with fascicular-storiform pattern

  • Pale eosinophilic cytoplasm

  • Monomorphic ovoid nuclei; inconspicuous mitotic activity

  • IHC: CD34

  • RNA-seq: COL1A1-PDGFB gene fusion

Dermatofibrosarcoma protuberans

  • Infiltrative; spindle cells with fascicular-storiform pattern

  • Pale eosinophilic cytoplasm

  • Monomorphic ovoid nuclei; occasional mitotic activity

  • Entrapment of subcutaneous adipose tissue with so-called "honeycomb" pattern

  • IHC: CD34

  • RNA-seq: COL1A1-PDGFB gene fusion

Dermatofibrosarcoma protuberans, pigmented (Bednar tumour)

  • Infiltrative; spindle cells with fascicular-storiform pattern

  • Pale eosinophilic cytoplasm

  • Monomorphic ovoid nuclei; occasional mitotic activity

  • Clusters of elongated cells with dense pigmentation

  • IHC: CD34

  • RNA-seq: COL1A1-PDGFB gene fusion

Dermatofibrosarcoma protuberans, myxoid

  • Protuberant; circumscribed; spindle-stellate cells with fascicular-storiform pattern

  • Scant eosinophilic cytoplasm

  • Monomorphic ovoid nuclei with small nucleoli; inconspicuous mitotic activity

  • IHC: CD34

  • RNA-seq: COL1A1-PDGFB gene fusion

Dermatofibrosarcoma protuberans, metastatic

  • Spindle-stellate cells with vague fascicular pattern

  • Pale eosinophilic cytoplasm

  • Ovoid nuclei with mild pleomorphism; occasional mitotic activity

  • Collagenous-myxoid stroma

  • IHC: CD34

  • RNA-seq: COL1A1-PDGFB gene fusion

Dermatofibrosarcoma protuberans, fibrosarcomatous (fibrosarcoma ex-DFSP)

  • Cellular; spindle cells with "herringbone" pattern

  • Pale amphophilic cytoplasm

  • Ovoid elongated nuclei with mild pleomorphism; conspicuous mitotic activity

  • IHC: CD34

  • RNA-seq: COL1A1-PDGFB gene fusion

Dermatofibrosarcoma protuberans

  • Infiltrative; spindle-ovoid cells with fascicular-storiform pattern

  • Pale eosinophilic cytoplasm with indistinct cell borders

  • Monomorphic ovoid nuclei; inconspicuous mitotic activity

  • IHC: CD34

  • RNA-seq: COL6A3-PDGFD gene fusion

  • PMID: 30014607

Dermatofibrosarcoma protuberans, neoadjuvant imatinib

  • Varied morphology:

    • Hypocellular spindle cells; sclerotic / hyalinized background

    • Hypocellular spindle-stellate cells; myxoid background

    • Hypercellular spindle cells with storiform pattern; scattered nuclear pleomorphism

  • RNA-seq: COL1A1-PDGFB gene fusion