Leiomyosarcoma



Leiomyosarcoma


Elizabeth A. Montgomery, MD










This leiomyosarcoma extended into the subcutis. It is composed of perpendicularly oriented fascicles of brightly eosinophilic cells. At scanning magnification, atypical nuclei stand out image.






There is no need to search for numerous mitoses to diagnose leiomyosarcoma, although mitotic counts assist in assigning a sarcoma grade. Note the bright pink color of the cytoplasm.


TERMINOLOGY


Abbreviations



  • Leiomyosarcoma (LMS)


Definitions



  • Malignant neoplasm composed of cells exhibiting smooth muscle differentiation


ETIOLOGY/PATHOGENESIS


Infectious Agents



  • Epstein-Barr virus (EBV) associated in immunosuppressed patients


  • Occasional examples are radiation associated


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Uncommon: 10-15% of extremity sarcomas


    • Most common overall sarcoma type if uterine and visceral examples are included


  • Age



    • Middle-aged adults


  • Gender



    • No gender preference overall


Presentation



  • Cutaneous LMS presents as a single nodule or plaque-like tumor



    • May be ulcerated or show serum crusting/hemorrhage


  • Deep soft tissue tumors present as a mass, often asymptomatic, in extremities



    • Retroperitoneum most common site


    • Vena cava examples often symptomatic


  • Uterine examples considered separately with unique diagnostic criteria


Treatment



  • Surgical excision



    • Radiation


    • Chemotherapy for metastatic tumors


Prognosis



  • Outcome site and stage dependent as with other sarcoma types



    • Lesions restricted to cutis essentially never metastasize



      • Some observers have advocated diagnosing them as “atypical smooth muscle tumors”


    • Subcutaneous lesions



      • Up to 1/3 of tumors metastasize


      • 10-20% of patients with subcutaneous lesion die of disease


    • Retroperitoneum: About 80% of patients die of disease, typically with metastases


    • Bone: Metastases in up to 1/2 of patients


    • Vena cava: 5- and 10-year survival 50% and 30%, respectively


    • Head and neck: Over 1/2 metastasize


MICROSCOPIC PATHOLOGY


Histologic Features



  • Perpendicularly oriented fascicles of spindle cells


  • Cells show brightly eosinophilic cytoplasm


  • Blunt-ended nuclei with nuclear atypia


  • Some examples are epithelioid-appearing


  • Any number of mitoses sufficient in subcutis, scrotal lesions, or deep soft tissue if nuclear atypia is present


  • In vulva, some observers offered > 5 mitosis per 10 HPF as “cutoff,” but recurrences reported in lesions with any mitotic activity


Predominant Pattern/Injury Type



  • Fascicular



Predominant Cell/Compartment Type



  • Mesenchymal, smooth muscle


Variant and Special Forms

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