Soft tissue
Fibroblastic / myofibroblastic tumors
Inflammatory myofibroblastic tumor of soft tissue

Author: Komal Arora, M.D. (see Authors page)

Revised: 12 September 2016, last major update July 2012

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PubMed Search: Inflammatory myofibroblastic tumor of soft tissue

Cite this page: Inflammatory myofibroblastic tumor of soft tissue. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissueinflammyofibro.html. Accessed December 11th, 2016.
Definition / General
Clinical Features
  • 1/3 have associated fever, growth failure, malaise, weight loss, anemia, thrombocytosis, polyclonal hyperglobulinemia and elevated sedimentation rate
  • Symptoms disappear after excision of mass (J Korean Med Sci 2002;17:699)
Prognostic Factors
Case Reports
Treatment
Gross Description
  • Circumscribed, not encapsulated
  • White tan mass with whorled fleshy or myxoid cut surface
  • May have focal hemorrhage, necrosis or calcification, mean 6 cm
Gross Images

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Tumor at the mesentery of proximal jejunum

Mesentery of both jejunum and ileum

Well circumscribed, grayish white

Micro Description
  • Myofibroblastic and fibroblastic spindle cells with inflammatory infiltrate of lymphocytes, plasma cells, eosinophils, histiocytes
  • Background of abundant blood vessels
  • Mixture of three patterns:
    • Resembling nodular fasciitis with elongated myofibroblasts containing abundant eosinophilic cytoplasm and vesicular nuclei, loose myxoid stroma with neutrophils, lymphocytes and eosinophils, but few plasma cells;
    • Cellular with spindled myofibroblasts and fibroblasts in more compact stroma, arranged as islands surrounded by fibromyxoid stroma with prominent plasma cells and mitotic figures;
    • Densely hyalinized stroma with few spindle cells, few plasma cells or lymphocytes
  • May have ganglion-cell like myofibroblasts
  • All 3 patterns have no nuclear pleomorphism, no atypical mitotic figures
  • Malignant behavior: associated with highly atypical polygonal cells with oval nuclei, prominent nucleoli, Reed-Sternberg like cells, atypical mitotic figures
Micro Images

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Images hosted on PathOut servers:

Case of the Week #400 - epithelioid inflammatory myofibroblastic sarcoma (EIMS):

ALK



Other images:

ALK, courtesy of Mark R. Wick, M.D.

Courtesy of Mark R. Wick, M.D.



Typical appearance of spindled myofibroblastic cells and inflammatory infiltrate

Inflammation obscures the underlying myofibroblastic proliferation

Spindle cells are evident at high power

Tumor with more fibrous stroma



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Myofibroblasts and inflammatory cells

Various images



Retroperitoneal tumor

Positive Stains
Electron Microscopy Description
  • Myofibroblastic cells and activated fibroblasts
Electron Microscopy Images

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Calcifying fibrous pseudotumor

Molecular / Cytogenetics Description
Molecular / Cytogenetics Images

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t(2;5) karyotype

ALK staining, FISH and karyotype



Images hosted on Nature servers:

Presence of ALK gene rearrangement

FISH for ALK

Differential Diagnosis