Myxoinflammatory Fibroblastic Sarcoma

Myxoinflammatory Fibroblastic Sarcoma

Elizabeth A. Montgomery, MD

This is a gross specimen of a myxoinflammatory fibroblastic sarcoma. This 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.



  • Acral myxoinflammatory fibroblastic sarcoma (MIFS), inflammatory myxohyaline tumor


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



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


  • Recurrences are common, but metastases are rare


General Features

  • Infiltrative masses


  • 1-10 cm, usually 3-4 cm


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 mixture of lymphoplasmacytic cells, eosinophils, neutrophils, and histiocytes

  • Lesional cells are fibroblasts ultrastructurally

  • Scattered enlarged atypical fibroblasts, some with macronucleoli

  • Areas with prominent myxoid change

    • Fibroblasts often vacuolated (“pseudolipoblasts”)

  • Low mitotic rate

    • Low proliferative index by Ki-67



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

  • Negative CD15, CD30, CD45 in cells with macronucleoli

  • No demonstration of various viral agents


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

  • t(2;6)(q31;p21.3) reported


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 and CD30, and are lymphoid rather than fibroblastic

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

  • Strongly CD34(+)

Viral Infection

  • Usually involves internal organs and lymph nodes

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

  • CMV effect best seen in stromal cells

  • HSV effect often seen in epithelial cells

  • Agents can be demonstrated by immunohistochemistry or molecular testing


  • Usually in proximal extremities of older persons

  • Typically superficial and lobulated rather than infiltrative

  • Richly vascular

  • Abundance of myxoid stroma

  • No hyalinized zones

  • Inflammatory cells a minor component

Epithelioid Sarcoma

  • Distal extremities of adults

  • Neoplastic cells surround zones of necrosis

    • Appearance mimics granulomatous process

  • Minimal inflammation

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

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

Clear Cell Sarcoma (“Melanoma of Soft Parts”)

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