Inflammatory myofibroblastic tumor

Bone
Other tumors of bone
Inflammatory myofibroblastic tumor

Author: Nat Pernick, M.D. (see Authors page)

Revised: 19 October 2016, last major update June 2005

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PubMed search: inflammatory myofibroblastic tumor [title] bone

Table of Contents

Cite this page: Inflammatory myofibroblastic tumor. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/boneIMT.html. Accessed July 14th, 2017.

Definition / general

Also called inflammatory fibrosarcoma or inflammatory pseudotumor
Very rare in bone

Radiology description

Destructive bone tissue that expands into soft tissue

Radiology images

Images hosted on other servers:

Osteolytic lesion with
irregular margin and
sclerotic rim, extend-
ing into soft tissue

Case reports

70 year old woman (Arch Pathol Lab Med 2000;124:1514)
Two cases in young adults (Am J Surg Pathol 1997;21:1166)

Gross description

Solitary, well demarcated, grayish yellow tumor, may expand into adjacent soft tissue

Microscopic (histologic) description

Cellular area with fascicles composed of thin spindle cells with eosinophilic cytoplasm, mild pleomorphism, frequent normal mitotic figures and infiltrate of lymphocytes and plasma cells
Hypocellular fibrous area with minimal inflammatory cells

Microscopic (histologic) images

Images hosted on other servers:

Fascicular, storiform and hypocellular areas

Alpha smooth muscle actin

Positive stains

Vimentin, alpha smooth muscle actin

Negative stains

Desmin, h-caldesmon, AE1 / AE3, CAM5.2

Molecular / cytogenetics description

May be neoplastic

Differential diagnosis

Leiomyosarcoma: more pleomorphism, atypical mitotic figures, fewer inflammatory cells, caldesmon+
Malignant fibrous histiocytoma: marked pleomorphism, inflammatory cells usually neutrophils and macrophages