Soft tissue
Fibrohistiocytic tumors
Benign fibrous histiocytoma (superficial)

Author: Vijay Shankar, M.D. (see Authors page)

Revised: 13 September 2016, last major update August 2012

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Benign fibrous histiocytoma [title]

Definition / General
  • Storiform pattern of bland spindle cells and foamy histiocytes centered in dermis with possible extension to subcutis
  • Variable hemosiderin, multinucleated giant cells, chronic inflammatory cells and pseudoepitheliomatous hyperplasia
Terminology
Epidemiology
  • Very common benign, indolent tumor of adults, common site is legs of women 20 - 50 years old
  • Slight female predominance
  • May be associated with trauma
  • Line of differentiation is uncertain
  • Multiple lesions may be associated with immunosuppression (Int J Dermatol 2008;47:723)
Pathophysiology
  • Fibroblasts cause strong expression of keratin 19 by keratinocytes and production of a galectin1 rich extracellular matrix, which may account for pseudoepitheliomatous hyperplasia (J Dermatol Sci 2009;55:18)
Clinical Features
  • Tan-brown (also pink-red, flesh colored, rarely blue), firm, mobile, painless papule < 2 cm in dermis
  • Size varies slightly with time; rarely > 5 cm and plaque-like (Australas J Dermatol 2008;49:106) or pedunculated (Case Rep Dermatol 2011;3:32)
  • Polypoid, flat, dome shaped or depressed
  • May dimple upon lateral compression; may have overlying scaling
Treatment
  • Excision; local recurrence is rare even with involved margins
  • Rarely is locally aggressive or metastatic (more common for facial lesions, with extension into subcutis)
Clinical Images

Images hosted on PathOut servers:

Breast skin, courtesy of Mark R. Wick, M.D.

Courtesy of Mark R. Wick, M.D.



Images hosted on other servers:

Dimpling when squeezed along margins

Gross Images

Images hosted on other servers:

Ulcerated cutaneous mas

Micro Description
  • Well defined but non-encapsulated
  • Overlying epidermis shows pseudoepitheliomatous hyperplasia and hyperpigmentation of basal cell layer
  • Grenz zone is usually present
  • Storiform pattern of spindled and bland fibroblasts and histiocyte-like cells in mid-dermis and subcutaneous tissue with infiltrative margins but sparing epidermis
  • Loose collagenous and rarely myxoid stroma
  • Spindle cells have scant cytoplasm, thin elongated nuclei with pointed ends
  • Nuclei almost touch each other, unlike smooth muscle lesions
  • Also foamy histiocytes with variable hemosiderin (Case Rep Dermatol 2011;3:32), some multinucleated giant cells, branching vessels & chronic inflammatory cells; rarely is marked eosinophilic infiltrate (European Journal of Dermatology 2011;21:138)
  • Often Touton giant cells (superficial and filled with hemosiderin), individual hyaline collagen bundles surrounded by tumor cells at periphery
  • 2% have 4 or more mitotic figures/10 HPF, but still benign behavior (J Cutan Pathol 2008;35:839)
  • Rare variants are balloon cell (Am J Dermatopathol 2007;29:197), clear cell, osteoclast like giant cells, signet ring (Am J Dermatopathol 2009;31:84)

  • Dermoscopy description:
    • Wide range of presentations (Arch Dermatol 2008;144:75)
    • Pigment network (72%, 3% are atypical), white scar-like patch (57%), different vascular structures (50%), white network (18%)
    • May resemble melanoma
Micro Images

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Images hosted on PathOut servers:

Tumor is more basophilic than surrounding dermis

Basophilia is due to increased cellularity

Sharp border between tumor and subcutis

Tumor cells are composed of histiocyte-like cells and foam cells

Tumor cells are mostly fibrous in this focus



Fat may be entrapped
at edge, but must differentiate
from infiltration of DFSP

Randomly arranged foam
cells, fibroblasts and histiocyte
-like cells; foam cells are
somewhat specific for this lesion

Less common finding
of predominately foam cells
and cholesterol clefts



Images courtesy of Mark R. Wick, M.D.:

Breast skin

Aneurysmal type

Cellular type

Deep penetrating



Granular cell change



Palisading type

Sclertoic type

Nuclear pleomorphism



Images hosted on other servers:

Various images

H&E and D2-40

Tumor with hyperplastic epithelium



Hyperplastic epidermis and sclerotic stroma

Foam cells with vacuolated cytoplasm



Fibroblastic cells with vacuolated cytoplasm in collagenous stroma

Spindle cell nodule

Paucicellular dermal tumor

Spindle cells in dense collagenous stroma



Dermoscopy images:

Pseudonetwork present

Central white scar-like patch, pigmented network and many brown globules

Different patterns

Various images

Positive Stains
Molecular / Cytogenetics Description
  • Often clonal
Differential Diagnosis