Nodular Fasciitis



Nodular Fasciitis


Elizabeth A. Montgomery, MD









Hematoxylin & eosin shows low magnification of nodular fasciitis. The lesion is nodular and reminiscent of granulation tissue. Note the moderate circumscription.






Hematoxylin & eosin shows a loose storiform pattern with cystic spaces image and background lymphocytes and extravasated erythrocytes.


TERMINOLOGY


Abbreviations



  • Nodular fasciitis (NF)


Synonyms



  • Pseudosarcomatous fasciitis


  • Subcutaneous pseudosarcomatous fibromatosis


Definitions



  • Rapidly growing myofibroblastic mass-forming proliferation that is often cellular and mitotically active but behaves in benign fashion



    • Typically displays loose storiform pattern, cystic spaces, and strands of keloid-like collagen


  • Intravascular fasciitis is rare variant of nodular fasciitis arising from small or medium-sized vessels



    • Presents as soft tissue mass with focal intravascular extension or multinodular predominantly intravascular mass


    • Despite intravascular location, lesion behaves in benign fashion with no tendency to recur or metastasize


  • Cranial fasciitis involves soft tissues of scalp and underlying skull of infants



    • Usually erodes bone but may penetrate through bone to involve meninges


    • Fragments of bone may be seen at periphery of lesion


    • Birth trauma presumed inciting stimulus


ETIOLOGY/PATHOGENESIS


Unknown



  • History of local trauma in subset


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Uncommon but comparatively common among soft tissue lesions


  • Age



    • 3rd-4th decades


  • Gender



    • M = F


Presentation



  • Subcutaneous mass


Treatment



  • Simple excision usually curative


Prognosis



  • Excellent prognosis


  • Seldom recurs, even if incompletely excised


MACROSCOPIC FEATURES


General Features



  • Well-marginated but unencapsulated


  • Variable mucoid appearance


Sections to Be Submitted



  • Usually entire lesion is submitted


Size



  • 2-3 cm mass


MICROSCOPIC PATHOLOGY


Histologic Features



  • Loose storiform, “feathery” pattern with tissue culture appearance, variable myxoid stroma, cystic spaces, strands of keloid-like collagen


  • Mitoses present but no atypical forms




  • Osteoclast-like giant cells found in most lesions if sought



    • Can be highlighted by CD68


  • Scattered lymphocytes but essentially no plasma cells


  • Extravasated erythrocytes



    • No associated hemosiderin


  • 3 forms reported: Myxoid, cellular, and fibrous



    • Loose correlation with duration of lesions


    • Myxoid lesion often resected within 10 days after coming to clinical attention


    • Cellular and fibrous forms resected after longer intervals


    • Some lesions show several patterns


  • Myofibroblastic differentiation results in expression of some smooth muscle immunohistochemical markers



    • Lesions can be mistaken for leiomyosarcomas when mitotically active


Predominant Pattern/Injury Type



  • Localized


Predominant Cell/Compartment Type



  • Mesenchymal, spindle


Variant Forms



  • Nodular myositis



    • Same as nodular fasciitis but intramuscular


    • Debate as to whether such cases are instead early myositis ossificans


  • Intravascular fasciitis



    • Typically affects head and neck and distal extremities


    • More solid than classic form


    • Typically displays abundant osteoclast-like giant cells


    • Easily mistaken for leiomyosarcoma based on mitoses


  • Cranial fasciitis



    • Lesion of infants sometimes attributed to birth trauma


    • Similar morphology to that of nodular fasciitis but more myxoid background


    • Some reported examples may be fibromatoses


    • Can involve skull itself


  • Subsets occur in specific locations



    • Spermatic cord (proliferative funiculitis)


    • Within nerves


ANCILLARY TESTS


Cytology



  • Shows myofibroblastic cells



    • Lesions are cellular, which can lead to erroneous impression of sarcoma on aspiration cytology

Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Nodular Fasciitis
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