Soft tissue
Fibrohistiocytic tumors
Benign fibrous histiocytoma (superficial)

Author: Engy Abdellatif M.B.B.Ch., Ph.D., M.D. (see Authors page)

Revised: 9 June 2017, last major update June 2017

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Benign fibrous histiocytoma [title]

Cite this page: Benign fibrous histiocytoma (superficial). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissuebfh.html. Accessed July 26th, 2017.
Definition / general
  • Fibrous histiocytomas are benign or malignant
  • Cutaneous benign fibrohistiocytic (BFH) tumors are among the most common soft tissue lesions, and have these crriteria:
    1. Commonly found on the skin
    2. Slow growing solitary nodule
    3. Made up of a mixture of fibroblastic and histiocytic cells
  • BFH is a neoplastic or quasi neoplastic mesenchymal soft tissue lesion with fibroblastic and histiocytic differentiation, commonly located in the dermis and subcutis and rarely in deep soft tissue
  • Essential features
    • Acanthosis or pseudoepitheliomatous hyperplasia of the overlying skin
    • 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
    Terminology
    • When located in the skin it is called "dermatofibroma"
    Epidemiology
    • Common, all races, all ages but more common in ages 20 - 49 years
    • Females > Males
    • 1/3 of cases show metachronous multiple tumors
    • Synchronous tumors have been reported in immunosuppressed and SLE patients
    Sites
    • Any part of the skin surface can be affected
    • Most common sites are the extremities
    • Rare sites are conjunctiva and larynx
    Pathophysiology
    • Clonal proliferation has been documented, but this does not prove it is neoplastic (Histopathology 2000;37:212)
    • Factor XIIIa labelling dendritic cells are consistently expressed, but MAC387, a histiocytic marker, is expressed less consistently
    • Epithelioid and atypical dermatofibroma variants show ALK gene rearrangement and overexpression
    Etiology
    • It is not clear whether fibrous histiocytoma is a reactive or neoplastic process
    • Often seems to appear after a minor injury to the skin such as a prick from a thorn, vaccination or an insect bite
    Diagrams / tables
    Images hosted on other servers:

    Dermoscopic patterns

    Clinical features
    • Elevated, pedunculated or dome shaped
      • Rare atrophic variant is flat or depressed
    • Can have variable colors, sometimes pink, pigmented, tan brown or blue black
    • Firm in consistency and measures from a few millimeters to a few centimeters in diameter
    • May dimple upon lateral compression; may have overlying scaling
    Case reports
    Treatment
    • Typical dermatofibromas have benign behavior with an excellent prognosis
    • Spontaneous regression has been reported in rare occasions¬†and this may leave a post inflammatory hypopigmentation
    • Wide excision is adequate to prevent recurrence, but local recurrence is rare even with involved margins
    • Rare cases of morphologically benign FH have locoregional or distant metastasis (Am J Surg Pathol 2013;37:484)
    Clinical images

    Scroll to see all 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:

    Dermatofibroma on the skin


    Dimpling when squeezed along margins

    Dermatofibroma on the right upper back

    A very flat dermatofibroma


    Dermatofibroma on the arm

    Side on view

    Dermatofibroma on the waist

    Cellular dermatofibroma



    Dermoscopy images:

    A central scar-like area associated with a peripheral pigment network


    Pseudonetwork present

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

    Dermoscopic appearance and close up

    Various images

    Dermoscopy
    • Has a wide range of presentations - the most classic dermoscopic pattern is a pigmented network and central white patch
    Gross images
    Images hosted on other servers:

    Ulcerated cutaneous mas

    Microscopic (histologic) description
    • A heterogeneous tumor, with a number of variants
    • Well defined but nonencapsulated, showing extension in the subcutis as radiating spikes
    • Overlying epidermis shows pseudoepitheliomatous hyperplasia and hyperpigmentation of basal cell layer; sometimes the overlying epidermis shows thinning
    • Grenz zone is usually present
    • Mixture of fibroblastic, myofibroblastic-like and histiocytic cells
    • Spindle cells have scant cytoplasm, thin elongated nuclei with pointed ends
    • Nuclei almost touch each other, unlike smooth muscle lesions
    • Arranged in a cartwheel or storiform pattern
    • Varying numbers of inflammatory cells, foam cells and siderophages can be seen
    • Touton giant cells may be seen
    • Bland spindle cells and mitosis are uncommon; in a small percentage of tumors, 4 or more mitotic figures/10 HPF have been reported but still behave as benign tumours
    • Variants can be categorized based on changes in the architecture, cellular and stromal content or both:
      • Architectural differences:
        • Deep penetrating
        • Atrophic
        • Aneurysmal
        • Palisading
      • Cellular / stromal content:
        • Aneurysmal variant: highly cellular with extensive cystic hemorrhage
        • Cellular: highly cellular and extends into the subcutaneous fat
        • Cholesterotic
        • Clear cell: clear cells present
        • Epithelioid variant: more than half the cells are polygonal or rounded with abundant eosinophilic cytoplasm
        • Hemosiderotic
        • Lipidized / ankle type: foamy macrophages surrounded by abundant sclerotic collagen bundles
        • Myxoid: myxoid changes
        • Palisading: nuclear palisading
    Microscopic (histologic) 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:

    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


    Various images

    H&E and D2-40

    Virtual slides
    Images hosted on other servers:

    Lump on back

    Excision biopsy of pigmented lesion right lower thigh

    Cystic lesion from forearm Sarcoma

    Skin of left upper arm

    Skin of back of neck

    Positive stains
    Negative stains
    • CD34 is used to differentiate between BFH and dermatofibrosarcoma protuberans
    Videos

    Dermatofibroma Diagnosis and Treatment

    Differential diagnosis
    Board review question #1
    How can you differentiate between dermatofibroma and dermatofibrosarcoma protuberans by using immunohistochemistry?

    1. Cannot - both are diffusely positive for CD34
    2. Cannot - both are negative for CD34
    3. Dermatofibrosarcoma protuberans and the cellular variant of benign fibrous histiocytoma are positive for CD34, but dermatofibroma is otherwise negative for CD34
    4. Dermatofibrosarcoma protuberans is negative for CD34 and dermatofibroma is positive for CD34
    Board review answer #1
    C. Dermatofibrosarcoma protuberans and the cellular variant of benign fibrous histiocytoma are positive for CD34, but dermatofibroma is otherwise negative for CD34.