Soft Tissue Tumors - Aneurysmal fibrous histiocytoma

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Soft Tissue Tumors

Fibrohistiocytic tumors

Aneurysmal fibrous histiocytoma

Reviewer: Vijay Shankar, M.D. (see Reviewers page)
Revised: 24 October 2012, last major update August 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Rare variant with dermal spindle cells and lakes of blood, but no endothelium

Terminology
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● First described in 1981 (Cancer 1981;47:2053)
● Early lesion also called hemosiderin variant of fibrous histiocytoma
● Similar to sclerosing hemangioma variant of fibrous histiocytoma, which has more prominent capillaries, but differs from lung lesion called sclerosing hemangioma

Clinical features
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● Usually extremities or trunk; often pigmented, rapid growth and pain (J Clin Pathol 1996;49:313)
● May have history of trauma (J Korean Med Sci 1989;4:159)

Case reports
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● 10 year old girl with leukemia (Pediatr Dermatol 2006;23:591)
● 38 year old man with abdominal lesion called hemosiderotic variant (Dermatology 2007;214:82)
● 48 year old woman with recurrent tumor (J Clin Pathol 2004;57:312)

Treatment and prognosis
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● Excision
● Tends to recur if there is incomplete excision
● Rarely metastasizes

Clinical images
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Exophytic lesion with slight scaling; irregular coloration mimics melanoma

Grayish brown atrophic shiny patch

Gross description
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● Blue, black or dark red cystic nodule
● Size varies from 0.5 to 4 cm
● Rarely presents as atrophic patch

Dermoscopy description
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● Multicomponent pattern with central blue/red homogeneous area, white structures, peripheral delicate pigment network and vascular structures (Br J Dermatol 2006;154:244); this pattern also present in some melanomas

Micro description
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● Storiform pattern of fibrohistiocytic cells (as in classic fibrous histiocytoma), but many cells are filled with hemosiderin
● Also large cystic spaces filled with blood, but without an endothelial lining
● Bizarre cells often present
● May have hemangiopericytoma-like pattern of cysts
● Periphery may have hyalinized collagen bundles surrounded by tumor cells (Histopathology 1995;26:323)
● Usually epidermal hyperplasia
● May have up to 10 MF/10 HPF

Micro images
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Non-endothelial lined clefts or lakes containing blood

Various images

Hemangiopericytoma-like pattern of cysts

Large irregularly shaped cysts resembling HPC

Large amounts of hemosiderin

Hemosiderin with marked sclerosis

Positive stains
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● Vimentin, Factor XIIIa (in areas without hemosiderin, J Dermatol 2002;29:744)
● Variable NKI-C3 (60%), smooth muscle actin (45%)

Negative stains
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● CD31, CD34 (confirms that cysts do not contain endothelium), Factor VIIIa, CD68
● Actin, desmin, cytokeratin, Ki67

Electron microscopy description
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● Hemosiderin containing histiocyte-like cells, fibroblast-like cells and intermediate cells
● No prominent proliferation of endothelial cells (Am J Dermatopathol 1995;17:179)

Molecular/cytogenetics description
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● Single case report of recurrent tumor with t(12;19) (Cancer Genet Cytogenet 2006;164:155)

Differential diagnosis
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● Angiomatoid fibrous histiocytoma: thick pseudocapsule, marked chronic inflammatory infiltrate and cystic areas of hemorrhage
● Spindle cell hemangioendothelioma: thick walled muscular blood vessels, organizing thrombi
● Angiosarcoma: lined by endothelial cells, variable atypia (APMIS 2006;114:744)
● Kaposi’s sarcoma: endothelial lined vessels are present (CD31+, CD34+), KSHV / HHV8+

End of Soft Tissue Tumors > Fibrohistiocytic tumors > Aneurysmal fibrous histiocytoma

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