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Soft tissue Tumors

Fibroblastic / myofibroblastic tumors

Elastofibroma


Reviewer: Komal Arora, M.D. (see Reviewers page)
Revised: 19 July 2012, last major update July 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Benign, poorly circumscribed pseudotumor of subscapular region, composed of collagen and coarse enlarged elastic fibers
● Reactive hyperplasia involving abnormal elastogenesis
● Also called elastofibroma dorsi
● First described in 1961 by Jarvi and Saxen (Acta Pathol Microbiol Scand 1961;51:83)

Sites:
● More common on apex of scapula, usually right sided
● Occasionally in deltoid muscle, infraolecranon area, hip, thigh, stomach
● May be multiple, bilateral or familial
● May be periosteal in origin
● Slightly different amino acids from elastin
● Has collagen types I-III (type II normally restricted to articular cartilage and ocular structures)

Epidemiology
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● Usually age 55+ years
● Associated with hard manual labor
● Related changes found at autopsy in 13-17% of elderly
● More common in women

Case reports
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● 55 year old woman (Case of the Week # 46)
● 69 year old man with tumor of hand (J Bone Joint Surg Br 1987;69:468)
● 69 year old woman with bilateral subscapular tumors and tumor surrounding a stomach ulcer (Am J Surg Pathol 1985;9:233)
● 78 year old man with multiple subcutaneous nodules (J Am Acad Dermatol 2004;50:126)

Treatment
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● Excise if symptomatic, does not recur

Clinical images
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Shoulder based tumors


Typical location (arrow)

Gross description
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● Ill defined, rubbery, gray-white fibrous tissue mixed with yellow streaks of elastin
● Up to 15 cm

Gross images
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Fibrocollagenous areas blend with fat (AFIP)

   
Poorly defined fibroelastic tumor entrapping fat


Gray-white fibrous tissue mixed with fat

Micro description
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● Collagen bundles alternate with large, thick eosinophilic elastic cylinders with a dense central core, elastic fibers may be fragmented into linear globules (beads on a string)
● Often has irregular interdigitation into adipose tissue

Micro images
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Paucicellular fibrous tissue mixed with fat


Thick, densely eosinophilic elastin bands are mixed with collagen


Elastin bands have serrated edges and are associated with detached globular elastin arranged like beads on a string


Thick bands of fibrous tissue (long arrows) intermixed with multiple regions of mature adipose tissue


Fibrous tissue mixed with elastin bands


Branched (arrow) and unbranched coarse elastin fibers mixed with collagen and adipose


H&E and elastic stain

           
Verhoeff elastin stain highlights elastin fibers and the bead-like arrangement of the elastin globules


Orcein (elastin) stain

           

       
Case of the Week #46

Cytology
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● Hypocellular smear with diagnostic aggregates of globules within a collagenous matrix (Diagn Cytopathol 2011 May 31 [Epub ahead of print], Acta Cytol. 2007;51:497, Anticancer Res 2002;22:3561)
● Altered elastic fibers have green-yellow autofluorescence with ultraviolet light (Diagn Cytopathol 2002;26:310)

Positive stains
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● Vimentin, elastic stains (fibers have dense core and irregular margins), CD34 in spindle cells (Virchows Arch 2006;448:195)

Negative stains
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● S100, desmin, smooth muscle actin, p53 (Ann Diagn Path 2002;6:94)

Electron microscopy description
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● Cylinders composed of immature amorphous elastic tissue, central core contains mature fibers, removed by elastase digestion (J Electron Microsc (Tokyo) 2006;55:89, Med Mol Morphol 2008;41:179)

Molecular
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● Xq12-q22 or #19 gains in 30% (Int J Mol Med 2002;10:277)

Differential diagnosis
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Nuchal fibroma: younger than 55 years, between scapula and vertebrae, dense collagen but no elastic fibers
Fibrolipoma: no elastic fibers
Desmoid fibromatosis: more cellular, infiltrates skeletal muscle, no elastic fibers

Additional references
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World J Surg Oncol 2007;5:15, Sarcoma 2008;2008:756565, APMIS 2007;115:115, Ann Thorac Surg 2007;83:1894
eMedicine, Stanford University

End of Soft Tissue Tumors > Fibroblastic / myofibroblastic tumors > Elastofibroma


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