Myxoinflammatory Fibroblastic Sarcoma



Myxoinflammatory Fibroblastic Sarcoma


Elizabeth A. Montgomery, MD









This is a gross specimen of a myxoinflammatory fibroblastic sarcoma. This particular lesion was highly infiltrative and clinically mistaken for pigmented villonodular tenosynovitis.






At scanning magnification, myxoinflammatory fibroblastic sarcoma displays a generous inflammatory background and scattered myxoid zones. Lymphoid cells are prominent at the edges of the field image.


TERMINOLOGY


Synonyms



  • Acral myxoinflammatory fibroblastic sarcoma, inflammatory myxohyaline tumor


Definitions



  • Low-grade fibroblastic sarcoma characterized by typical acral presentation and inflammatory background often rich in eosinophils


CLINICAL ISSUES


Presentation



  • Slow-growing infiltrative mass usually affecting distal extremities (hands and feet) of adults


Prognosis



  • Recurrences are common, but metastases are rare


MACROSCOPIC FEATURES


General Features



  • Infiltrative masses


Size



  • 1-10 cm, usually 3-4 cm


MICROSCOPIC PATHOLOGY


Histologic Features



  • Poorly marginated tumor with fibrosis, hyalinization, myxoid stroma, and inflammatory components



    • Various lesions have different proportions of each component


  • Inflammatory component shows variable mixtures of lymphoplasmacytic cells, eosinophils, neutrophils, histiocytes


  • Lesional cells are fibroblasts ultrastructurally


  • Scattered enlarged atypical fibroblasts, some with macronucleoli


  • Areas with prominent myxoid change



    • Fibroblasts often vacuolated as “pseudolipoblasts”


  • Low mitotic rate



    • Low proliferative index using Ki-67


ANCILLARY TESTS


Immunohistochemistry



  • Variable expression of CD34, CD68, EGFR, CD163, CD117, EMA


  • Negative CD15, CD30, CD45 in cells with macronucleoli


  • No demonstration of various viral agents


Cytogenetics



  • t(1;10) and amplification of 3p11-12, which myxoinflammatory fibroblastic sarcoma shares with hemosiderotic fibrolipomatous tumor


  • t(2;6)(q31;p21.3) reported


DIFFERENTIAL DIAGNOSIS


Extranodal Hodgkin Disease



  • Patients usually have history of nodal disease


  • Usually no myxoid areas


  • Background mostly lymphoid cells, neutrophils not common


  • Reed-Sternberg cells label with CD15, CD30, and are lymphoid rather than fibroblastic


Myxofibrosarcoma



  • Usually in proximal extremities of older persons


  • Typically superficial and lobulated rather than infiltrative


  • Abundance of myxoid stroma


  • Richly vascular




  • Inflammatory cells a minor component


  • No hyalinized zones


Pigmented Villonodular Tenosynovitis



  • Also termed tenosynovial giant cell tumor, diffuse type


  • Often presents in knee joint area of young women


  • Proliferated around joint space


  • Proliferation of uniform rounded cells


  • Background of hemosiderin, histiocytes, lymphoplasmacytic cells


  • Eosinophils and neutrophils not a feature


  • Not myxoid


  • No enlarged atypical cells


Hemosiderotic Fibrohistiocytic Lipomatous Lesion



  • Classically involves the feet


  • May form spectrum with both myxoinflammatory fibroblastic sarcoma and with pleomorphic hyalinizing angiectatic tumor



    • However, no metastases have been recorded for either hemosiderotic fibrohistiocytic lipomatous lesion or pleomorphic hyalinizing angiectatic tumor


    • Shares t(1;10) and amplification of 3p11-12


  • Tracks along connective tissue septa


  • Spindle cells, abundant hemosiderin, histiocytes


  • Neutrophils and eosinophils not features


  • Strongly CD34(+)


Viral Infection



  • Usually involves organs and lymph nodes


  • Infectious agents can be demonstrated by immunohistochemistry or molecular testing


  • Viral cytopathic effect consists of nuclear (Cytomegalovirus and herpes simplex virus) or cytoplasmic (Cytomegalovirus) inclusions


  • Cytomegalovirus effect best seen in stromal cells


  • Herpes simplex viral effect often seen in epithelial cells


Epithelioid Sarcoma



  • Distal extremities of adults


  • Neoplastic cells surround zones of necrosis



    • Appearance mimics granulomatous process


  • Minimal inflammation


  • CD34(+), pankeratin(+), CK5/6(-), loss of nuclear INI1


  • Malignant



    • Metastases to regional nodes as well as systemic metastases and death

Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Myxoinflammatory Fibroblastic Sarcoma
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