Sclerosing Pseudovascular Rhabdomyosarcoma



Sclerosing Pseudovascular Rhabdomyosarcoma


David R. Lucas, MD





Key Facts


Terminology



  • Variant of RMS characterized by extensive stromal fibrosis and pseudovascular, microalveolar, or cordlike architecture


Clinical Issues



  • Rare; only 34 reports


  • Adults and children


  • Median age: 30 years; range: 0.3-79 years


  • Extremities and head and neck most common


  • Poor prognosis


Microscopic Pathology



  • Hyalinizing stromal fibrosis



    • Can mimic osteoid or chondroid matrix


  • Small round blue cells or spindle cells


  • Pseudovascular, microalveolar, cord-like, single cell strand patterns


  • Solid cellular areas in some


  • Spindle cell fascicular areas in some


  • Rare rhabdomyoblasts


  • Only focal myogenin staining


Top Differential Diagnoses



  • Alveolar RMS


  • Sclerosing epithelioid fibrosarcoma


  • Angiosarcoma


  • Osteosarcoma


  • Infiltrating carcinoma


  • Mesenchymal chondrosarcoma


  • Extraskeletal myxoid chondrosarcoma






Sclerosing pseudovascular rhabdomyosarcoma most often affects the extremities and the head and neck. This MR image depicts a destructive mass image involving the maxillary sinus of a 26-year-old man.






Sclerosing RMS is characterized by cords and clusters of small round cells or spindle cells and extensive hyalinizing fibrosis. Poorly cohesive cell clusters resemble vascular structures image.


TERMINOLOGY


Abbreviations



  • Rhabdomyosarcoma (RMS)


Synonyms



  • Sclerosing RMS, carcinoma-like RMS, microalveolar RMS, desmoplastic RMS


Definitions



  • Variant of RMS characterized by extensive stromal fibrosis and pseudovascular, microalveolar, or cord-like architecture


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Rare; only 34 reports


  • Age



    • Adults and children


    • Median age: 30 years; range: 0.3-79 years


Site



  • Extremities and head and neck most common


Presentation



  • Painless mass in extremity


  • Obstructive symptoms in head and neck


Treatment



  • Surgical approaches



    • Wide excision


  • Adjuvant therapy



    • Chemotherapy &/or radiotherapy


Prognosis



  • Poor


  • Often unresectable


  • Local recurrence: 25%


  • Metastasis: 20%


MACROSCOPIC FEATURES


General Features



  • White to tan, firm to fleshy, hemorrhagic areas


Size



  • Median: 6 cm; range: 0.3-12 cm


MICROSCOPIC PATHOLOGY


Histologic Features



  • Hyalinizing stromal fibrosis



    • Can mimic osteoid or chondroid matrix


  • Pseudovascular, microalveolar, cord-like, single cell strand patterns


  • Solid cellular areas in some


  • Spindle cell fascicular areas in some


Cytologic Features



  • Small round blue cells and spindle cells


  • Scant eosinophilic or clear cytoplasm


  • Rare rhabdomyoblasts


DIFFERENTIAL DIAGNOSIS


Alveolar Rhabdomyosarcoma



  • Larger alveolar spaces


  • More cohesive growth pattern


  • Wreath-like giant cells in most


  • Lacks spindle cells


  • Very diffuse myogenin staining


  • t(2:13) or t(1:13) rearrangement in majority


Sclerosing Epithelioid Fibrosarcoma



  • Cords and single cell strands


  • Epithelioid cytology


  • Desmin(-)


  • MYOD1(-), myogenin(-)


  • Some have t(7;16) with FUS-CREB3L2 fusion



Angiosarcoma

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Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Sclerosing Pseudovascular Rhabdomyosarcoma

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