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Skin / Soft Tissue Tumors

Aneurysmal fibrous histiocytoma

Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.

Reviewer: David Lucas, M.D., University of Michigan Health Systems (January 2009)

Revised: 26 June 2009, last major update June 2009

Definition

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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

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● Usually extremities or trunk; often rapid growth and pain (J Clin Pathol 1996;49:313)

Case reports

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● 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; rarely metastasizes

Gross description

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● Blue, black or dark red; cystic

Gross images

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Exophytic lesion with slight scaling; irregular

coloration mimics melanoma

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 may also be 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                             Numerous blood filled cysts

Aneurysmal                                         No endothelial lining                          Squamous lining

changes                                                is present                                             (uncommon finding)

Squamous lining                                 Hemangiopericytoma-like                Large irregularly shaped

(high power)                                        pattern of cysts                                  cysts resembling HPC

Large amounts                                   Hemosiderin with                               Empty spaces were

of hemosiderin                                    marked sclerosis                               filled with blood

Old and new hemorrhage

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)

Electron microscopy

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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

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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

● 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 Skin / Soft Tissue Tumors > Aneurysmal fibrous histiocytoma

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