Cutaneous Malignant Fibrous Histiocytoma/Pleomorphic Sarcoma



Cutaneous Malignant Fibrous Histiocytoma/Pleomorphic Sarcoma


Khin Thway, BSc, MBBS, FRCPath










This cutaneous pleomorphic sarcoma is seen in the papillary dermis. Note the normal overlying epidermis without atypia or junctional activity, helping to exclude squamous cell carcinoma and melanoma.






Microscopically, pleomorphic undifferentiated sarcoma is hypercellular with sheets of markedly anaplastic spindled and epithelioid cells, including bizarre image and multinucleated image forms.


TERMINOLOGY


Synonyms



  • Pleomorphic sarcoma


  • Undifferentiated high-grade sarcoma


  • Malignant fibrous histiocytoma (MFH)


Definitions



  • Anaplastic sarcoma composed of pleomorphic spindle and polygonal cells



    • No other definable differentiation, other than fibroblastic or myofibroblastic


  • Morphologic pattern shared by poorly differentiated or anaplastic tumors of different lineages



    • Diagnosis of pleomorphic sarcoma is therefore one of exclusion


ETIOLOGY/PATHOGENESIS


Environmental Exposure



  • Can occur at site of previous irradiation


  • Rarely secondary to chronic ulceration or scarring


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Most common adult soft tissue sarcoma


    • Incidence increases with age


  • Age



    • Older adults


    • Very rare in adolescents and young adults


  • Gender



    • Slight male predominance


Site



  • Most are in deep soft tissue


  • Smaller numbers occur superficially in subcutaneous tissue



    • Dermal lesions are considered atypical fibroxanthoma (AFX) and have much better prognosis


  • Most in extremities (lower limb > upper limb)


  • May also arise on trunk


Presentation



  • Enlarging mass


  • Small proportion of patients have metastases at presentation


Prognosis



  • Usually high-grade tumors


  • Propensity for local recurrence and metastasis


  • Superficial tumors have better prognosis than deep ones


  • Myoid differentiation is prognostically adverse, with earlier metastasis



    • Applies whether differentiation is morphologic (leiomyosarcoma, myofibrosarcoma, rhabdomyosarcoma) or only immunohistochemical (actin, desmin)


MACROSCOPIC FEATURES


General Features



  • Lobulated


  • Generally circumscribed


  • Heterogeneous cut surface



    • Firm, solid, and softer myxoid areas


  • Necrosis and hemorrhage


Sections to Be Submitted

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Cutaneous Malignant Fibrous Histiocytoma/Pleomorphic Sarcoma

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