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Soft tissue Tumors

Fibroblastic / myofibroblastic tumors

Giant cell fibroblastoma


Reviewer: Komal Arora, M.D. (see Reviewers page)
Revised: 21 July 2012, last major update July 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Rare childhood fibroblastic tumor of intermediate malignancy with floret-like giant cells and ectatic pseudovascular spaces lined by stromal cells and giant cells
● Part of WHO classification for skin tumors, not soft tissue tumors
● Appears to evolve into DFSP by genomic gains of COL1A1-PDGFB (Genes Chromosomes Cancer 2008;47:260)
● Considered the juvenile form of DFSP, as both have the same translocation (Am J Surg Pathol 2003;27:27, Arch Pathol Lab Med 1996;120:1052, Ann Diagn Pathol 2007;11:81)

Epidemiology
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● Usually children less than 10 years old, 2/3 male
● Painless nodule of subcutis, usually in trunk, extremities, head and neck
● 50% recur but recurrences are controllable, no metastases

Case reports
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● 3 year old boy with recurrent knee lesion (Pathol Oncol Res 2003;9:249)
● 28 year old woman with vulvar tumor (J Low Genit Tract Dis 2007;11:112)

Gross description
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● Poorly circumscribed, gray to yellow mucoid mass that is difficult to completely excise, usually in subcutis

Micro description
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● Dermis and subcutis contains hyperchromatic spindle or stellate shaped cells in a collagenous or myxoid matrix with scattered hyperchromatic, multinucleated, floret-like giant cells with prominent nucleoli, similar to those in pleomorphic lipomas
● Ectatic pseudovascular spaces are lined by a discontinuous row of floret-like cells and tumor cells
● Honeycomb or parallel pattern of infiltration
● Also hyalinized area, perivascular lymphocytes in onionskin pattern, intralesional hemorrhage
● Often foci of DFSP
● No histiocyte-like cells, no mitotic figures

Micro images
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Ectatic pseudovascular spaces are lined by giant cells


Stroma has giant cells and myxoid stroma


Stroma is fibrotic with giant cells but sparse angiectoid spaces in this case


Multinucleated stromal giant cells have vesicular nuclei and prominent nucleoli, but smaller spindle cells have indistinct nucleoli

Trunk tumor #1, #2, #3

Cytology
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● Moderately cellular smears with mononuclear cells, usually single but occasionally in clusters
● Most cells have no/scanty cytoplasm, bland nuclei with small nucleoli
● Nuclear membranes often have notches, creases or folds
● Rare multinucleated giant cells with bland oval nuclei
● No necrosis, no mitotic figures (Diagn Cytopathol 2002;26:398, Arch Pathol Lab Med 2001;125:1091)

Cytology images
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Various images

Positive stains
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● Vimentin, CD34, CD99 (40%, J Cutan Pathol 2008;35:647)
● Variable actin

Negative stains
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● S100, CD31, Factor VIII, keratin, desmin, HMB45

Molecular
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● t(17,22)(q22;q13) - creates fusion of collagen type 1 alpha 1 gene and platelet derived growth factor B chain gene
● Also supernumerary ring chromosomes derived from t(17;22)

Electron microscopy description
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● Myofibroblasts or fibroblasts

Differential diagnosis
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● Angiosarcoma: older adults in head and neck, vascular tumor, cells have enlarged atypical nuclei, mitotic figures present
● Hemangioma: vascular tumor, no giant cells, CD31+
● Neurofibroma with ancient change: no ectatic vascular spaces, S100+
● Pleomorphic liposarcoma: pleomorphic cells are similar, but remaining lesion has lipoblasts and lacks collagenous matrix

Additional references
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Stanford University

End of Soft Tissue Tumors > Fibroblastic / myofibroblastic tumors > Giant cell fibroblastoma


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