Leiomyosarcoma



Leiomyosarcoma


Bruce M. Wenig, MD





Key Facts


Terminology



  • LMS: Malignant tumor of smooth muscle


Etiology/Pathogenesis



  • May develop following irradiation or cyclophosphamide exposure


  • Appears to arise from vascular structures


  • Link between LMS and Epstein-Barr virus (EBV) identified



    • Occurs in immunocompromised patients


Clinical Issues



  • Approximately 4% arise in head and neck


  • Increased incidence in immunocompromised patients


Microscopic Pathology



  • Interlacing fascicular to storiform bundles of spindle-shaped cells



    • Typically intersect at right angles


  • Neoplastic cells are elongated (spindle) with centrally located, blunt-ended, cigar-shaped nuclei and eosinophilic cytoplasm


  • Perinuclear vacuole or clear halo may be seen, giving nucleus an indented or concave contour


  • Variable degree of cellular anaplasia with nuclear pleomorphism, nuclear hyperchromasia, and increased mitotic activity (typical and atypical forms)


  • Actins (smooth muscle and muscle specific) positive


  • Criteria for malignancy



    • Tumors with 1-4 mitoses per 10 HPF considered potentially malignant especially in conjunction with nuclear atypia and necrosis


    • > 4 mitoses per 10 HPF is malignant







Sinonasal spindle-shaped cellular proliferation is shown with nuclear pleomorphism and increased mitotic activity image. The overall mitotic count was ≥ 4 mitoses per 10 high-power fields.






The presence of smooth muscle actin staining supports the light microscopic features in leiomyosarcoma (LMS). As head and neck LMS is rare, differentiation is required from other spindle cell neoplasms.


TERMINOLOGY


Abbreviations



  • Leiomyosarcoma (LMS)


Definitions



  • Malignant tumor of smooth muscle


ETIOLOGY/PATHOGENESIS


Environmental Exposure



  • May develop following irradiation or cyclophosphamide exposure


Infectious Agents



  • Link between LMS and Epstein-Barr virus (EBV) identified


  • Occurs in immunocompromised patients


Histogenesis



  • Appears to arise from vascular structures



    • Due to relative lack of smooth muscle in head and neck region


    • Other than relationship to vascular walls, histology similar to non-vascular-derived LMS


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Approximately 4% arise in head and neck


    • Increased incidence in immunocompromised patients



      • Post-transplantation (e.g., kidney, heart, liver)


      • AIDS


      • Epstein-Barr virus (EBV) found in these tumors, termed EBV smooth muscle tumors (EBVSMT)


      • Clonal EBV DNA and EBV surface receptor protein


      • Different episomal DNA clones found in separate tumors in same patient; suggests multifocal tumor rather than metastatic disease


  • Age



    • Non-immunocompromise-associated LMS



      • Occurs in wide age range


      • Most common in 6th decade


    • Immunocompromise-associated LMS



      • Tends to occur in children or young adults


  • Gender



    • Equal gender distribution


Site



  • Non-immunocompromise-associated LMS



    • Most common sites



      • Oral cavity (buccal mucosa, gingiva, tongue, floor of mouth)


      • Sinonasal tract


      • Skin and subcutaneous tissue


    • Less common sites



      • Larynx


      • Trachea


      • Neck


      • Hypopharynx


      • Orbit


      • External auditory canal


  • Immunocompromise-associated LMS



    • Tend to occur in relationship to viscera (e.g., GI tract, lung)


    • May be multifocal


Presentation



  • Nasal obstruction


  • Pain


  • Epistaxis


  • Painless mass


  • Ulceration


Treatment



  • Surgical approaches



    • Radical surgical excision




      • Treatment of choice


  • Radiation and chemotherapy are of questionable utility


Prognosis

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Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Leiomyosarcoma

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