Dermatofibrosarcoma Protuberans



Dermatofibrosarcoma Protuberans


David Cassarino, MD, PhD










Dermatofibrosarcoma protuberans (DFSP) is often characterized clinically by an exophytic, multinodular growth with areas of interposed flattening or atrophy.






Low magnification of a DFSP shows deep dermal and subcutaneous image involvement by a cellular spindle cell tumor with fat entrapment. Epidermis is separated from tumor by thin grenz zone image. (Courtesy T. Mentzel, MD.)


TERMINOLOGY


Abbreviations



  • Dermatofibrosarcoma protuberans (DFSP)


Synonyms



  • Bednar tumor (pigmented DFSP)


Definitions



  • Low-grade malignant spindle cell tumor of skin characteristically showing prominent storiforming


ETIOLOGY/PATHOGENESIS


Unknown in Most Cases



  • Rare cases reportedly associated with previous trauma, burns, or arsenic exposure


Genetics



  • Rearrangements of collagen 1A1 (COL1A1)/plateletderived growth factor B (PDGFB)


  • Characteristic t(17;22) detected in most cases



    • Can be detected by FISH or PCR studies for the fusion protein


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Uncommon tumors


  • Age



    • Typically occurs in young adults


    • Rare congenital cases reported


  • Gender



    • Male predominance


Site



  • Most often present on trunk or extremities


  • Rarely occur on head and neck


Presentation



  • Dermal and subcutaneous nodular/multinodular or plaque-like mass


Natural History



  • Slowly progressive, locally aggressive tumor


Treatment



  • Optimal treatment is complete surgical excision


  • Imatinib has been used for locally extensive and metastatic disease



    • Complete response reported in up to 50% of cases


Prognosis



  • Excellent in most cases


  • Local recurrences in up to 30% of cases


  • Very low metastatic potential (and essentially only in cases with fibrosarcomatous transformation)


MACROSCOPIC FEATURES


General Features



  • Polypoid, multinodular, or bosselated-appearing tumor



    • Rare cases may be atrophic appearing


  • Cut surface usually gray-white


  • May show hemorrhage and cystic changes


Size



  • Range: 1-10 cm


MICROSCOPIC PATHOLOGY


Histologic Features



  • Dermal and subcutaneous involvement


  • Proliferation of monomorphic spindle-shaped cells


  • Arrayed in storiform or cartwheel patterns


  • Lesional cells typically lack significant pleomorphism



    • Elongated spindle-shaped nuclei



    • Mild nuclear hyperchromasia, small to inconspicuous nucleoli


    • Moderate amounts of eosinophilic cytoplasm


  • Mitoses are usually infrequent (< 4/10 HPF) and not atypical



    • Increased mitoses and atypical forms are seen with fibrosarcomatous change


  • Necrosis is usually absent


  • Adnexal structures entrapped but not obliterated


  • Subcutaneous areas typically show “honeycombing” fat entrapment


  • Myxoid stromal change may be prominent in some cases


Cytologic Features



  • Elongated spindle-shaped cells with hyperchromatic-staining nuclei, small or absent nucleoli, and eosinophilic-staining cytoplasm


Variants



  • Bednar tumor



    • Pigmented DFSP due to intratumoral population of benign melanocytes


    • No prognostic significance


  • Giant cell fibroblastoma (GCFB)



    • Clinical: Occurs in children and young adults


    • Histologic features are distinctive



      • Proliferation of spindled cells and giant cells with nuclear hyperchromasia


      • Pseudovascular spaces lined by the giant cells


    • Mutations involving COL1A1/PDGFR (same as in DFSP)


ANCILLARY TESTS


Immunohistochemistry

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Dermatofibrosarcoma Protuberans
Premium Wordpress Themes by UFO Themes
%d bloggers like this: