Dermatofibrosarcoma Protuberans



Dermatofibrosarcoma Protuberans


Thomas Mentzel, MD

Cyril Fisher, MD, DSc, FRCPath





Key Facts


Terminology



  • Dermatofibrosarcoma represents superficially located low-grade fibroblastic sarcoma that may show progression to fibrosarcomatous dermatofibrosarcoma protuberans


Clinical Issues



  • Young adults


  • Rare in childhood


  • Trunk (chest, back, shoulder, abdominal wall)


  • Proximal > distal extremities > head/neck region


  • Slowly growing nodular dermal neoplasm


  • Wide excision is necessary


  • Imatinib treatment in advanced and metastatic cases


  • Increased number of often repeated local recurrences


  • Metastases are extremely rare (< 0.5%)


  • May show progression to fibrosarcomatous DFSP


Microscopic Pathology



  • Diffuse infiltration of dermis and subcutis


  • Infiltration along fibrous septa of subcutaneous fat


  • Characteristic honeycomb infiltration of subcutaneous fat


  • Storiform growth


  • Uniform spindled tumor cells


  • Homogeneous expression of CD34


  • Giant cell fibroblastoma



    • Hypocellular neoplasms with angiectoid spaces and multinucleated giant cells


  • Fibrosarcomatous DFSP



    • Abrupt or gradual transition


    • Cellular spindle cell fascicles with increased atypia and proliferative activity






Dermatofibrosarcoma protuberans is characterized clinically by an exophytic, multinodular growth in most cases.






Low-power view of a dermatofibrosarcoma protuberans shows the characteristic diffuse infiltration of subcutaneous fat by neoplastic cells that grow along fibrous septa image.


TERMINOLOGY


Abbreviations



  • Dermatofibrosarcoma protuberans (DFSP)


Definitions



  • Superficially located low-grade fibroblastic sarcoma


  • Can progress to fibrosarcomatous dermatofibrosarcoma protuberans


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Rare neoplasm


    • One of most frequent superficially located sarcomas


  • Age



    • Young adults


    • Rare in childhood or older age


  • Gender



    • Slight male predominance


Site



  • Trunk (chest, back, shoulder, abdominal wall)


  • Proximal extremities > distal extremities


  • Head and neck region


  • Rare in genital areas


Presentation



  • Slowly growing nodular dermal neoplasm


  • Often history of slow but persistent growth


  • Can show rapid enlargement due to tumor progression


  • Can show rapid enlargement in pregnancy


  • Rarely plaque-like growth


Treatment



  • Surgical approaches



    • Wide excision (2-3 cm)


  • Adjuvant therapy



    • Imatinib treatment in advanced and metastatic cases


Prognosis



  • Locally aggressive growth


  • Increased number of often repeated local recurrences


  • Metastases extremely rare (< 0.5%)


  • May progress to fibrosarcomatous DFSP


MACROSCOPIC FEATURES


General Features



  • Indurated dermal plaques


  • 1 or more tumor nodules



    • Multiple protuberant tumors are often seen in recurrent cases


  • Firm gray-white cut surface


  • Usually no tumor necrosis


  • Rarely subcutaneous


Sections to Be Submitted



  • Numerous sections have to be submitted


  • Resection margins have to be carefully assessed


Size



  • May reach considerable size


MICROSCOPIC PATHOLOGY


Histologic Features



  • Diffuse infiltration of dermis and subcutis


  • Infiltration along fibrous septa of subcutaneous fat



    • Characteristic honeycomb pattern


    • Tumor cells encase skin appendages


  • Storiform growth pattern


  • Uniform spindled tumor cells



    • Plump spindled or elongated wavy nuclei


    • Only mild cytologic atypia, < 5 mitoses per 10 high-power fields


  • Collagenous stroma with small vessels


  • May contain pigmented melanocytic cells (pigmented DFSP, so-called Bednar tumor)




  • May show prominent myxoid changes (myxoid DFSP)


  • May contain bundles and nests of myofibroblastic cells (DFSP with myoid differentiation)


  • May rarely show flat, plaque-like growth (plaque-like DFSP, atrophic DFSP)


  • May rarely show granular cell changes (granular DFSP)


Margins



  • Ill defined, infiltrative


Predominant Pattern/Injury Type



  • Diffuse


Predominant Cell/Compartment Type



  • Spindle


  • Fibroblast


Giant Cell Fibroblastoma



  • Primarily affects children in 1st decade of life, rarely adults


  • Strong male predilection


  • Locally aggressive neoplasm, frequent local recurrence


  • Metastases have not been reported yet


  • Hypocellular, with myxoid to collagenous stroma


  • Spindled tumor cells and scattered mono- &/or multinucleated giant cells


  • Irregular branching angiectoid spaces


Fibrosarcomatous DFSP



  • Represents morphologic form of progression (grade 2 malignancy)



    • 10-15% metastasize, and sometimes cause death


  • Occurs de novo or more rarely in local recurrence


  • Abrupt or gradual fibrosarcomatous transformation


  • Often nodular, rather well-circumscribed growth


  • Cells arranged in cellular “herringbone” fascicles


  • Increased atypia and mitotic index


  • Increased p53 expression

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Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Dermatofibrosarcoma Protuberans

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