Skin nonmelanocytic tumor

Fibrous, fibrohistiocytic and myofibroblastic neoplasms

Dermatofibroma (cutaneous fibrous histiocytoma)


Resident / Fellow Advisory Board: Josephine K. Dermawan, M.D., Ph.D.
Editorial Board Member: Kiran Motaparthi, M.D.
Brandon Zelman, D.O.
Jodi Speiser, M.D.

Minor changes: 7 October 2021

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PubMed Search: Benign fibrous histiocytoma [TI] free full text[sb]

Brandon Zelman, D.O.
Jodi Speiser, M.D.
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Cite this page: Zelman B, Speiser J. Dermatofibroma (cutaneous fibrous histiocytoma). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissuebfh.html. Accessed October 24th, 2021.
Definition / general
  • Dermatofibromas (also known as fibrous histiocytomas) are a spectrum of benign dermal based lesions with fibroblastic and histiocytic differentiation
  • There is debate as to whether dermatofibroma is a reactive or neoplastic process
Essential features
  • Benign dermal based, nodular proliferation of fibroblasts and histiocytes
  • Collagen trapping at periphery and follicular induction commonly seen
  • IHC is nonspecific for dermatofibroma
Terminology
  • Benign fibrous histiocytoma and fibrous histiocytoma
ICD coding
  • ICD-10: D23 - benign neoplasm of skin
  • ICD-11: 2F23.0 - dermatofibroma
Epidemiology
Sites
  • Typically occurs on distal extremities (legs > arms > trunk)
  • May present on any part of the skin surface
Pathophysiology
  • Cause unknown
  • No evidence associates it with insect bites or trauma
Etiology
Diagrams / tables

Images hosted on other servers:

Various presentations under dermoscopy

Clinical features
  • Painless
  • 5 mm - 2 cm
  • Variable color: skin colored to brown to purple
  • Variable shape: plaques, nodules or polyps
  • Covered by intact skin
  • Suspected by pinching the nodule between the fingers and observing that the tumor is fixed within the dermis
  • Pinch sign: overlying skin dimples on pinching the lesion (An Bras Dermatol 2014;89:472)
Diagnosis
  • Combination of clinical and histologic findings
Prognostic factors
Case reports
Treatment
  • Complete excision is curative
  • Wide local excision is adequate to prevent recurrence
  • Spontaneous regression has been reported
Clinical images

Images hosted on other servers:

Dermatofibroma of the skin

Dermatofibroma of the skin

Pinch sign of dermatofibroma


Hyperpigmented dermatofibroma

Numerous eruptive dermatofibromas

Dermatofibroma of the lower lip

Dermatofibroma presenting as eruptive papules

Dermatofibroma of the shoulder


Patterns of dermatofibroma

Vascular structures in dermatofibromas

Other dermoscopic structures

Gross description
  • Most classic pattern: pigment network and central white patch
  • Wide range of presentations
Gross images

Images hosted on other servers:
Ulcerated cutaneous mass

Polypoid, ulcerated mass

Microscopic (histologic) description
  • Symmetric and predominantly dermal based
  • Relatively circumscribed but have irregular and unencapsulated borders
  • Patterns range from diffuse to reticular to hemangioma-like to keloid-like
  • Classic pattern: storiform, pinwheel or curlicue pattern
    • Made up of spindled fibroblasts or histiocytes
  • Some areas densely cellular, while others are sclerotic and hypocellular
    • Early lesions: more cellular
    • Later lesions: more sclerotic
  • Spindled cells: thin, elongated nuclei with pointed ends and eosinophilic cytoplasm
  • Histiocytic cells: epithelioid shaped cells with abundant pale cytoplasm
  • May see varying amounts of inflammatory cells
  • Cytologic atypia and pleomorphism are variable
  • Mitotic activity is variable
  • Touton giant cells and ringed lipidized siderophages may be present
  • Collagen trapping at periphery
    • Spheres of eosinophilic collagen (collagen balls) surrounded by the fibroblast proliferation
  • Grenz zone (sparing of the superficial papillary dermis) commonly seen
  • Follicular or sebaceous induction and basilar hyperpigmentation
  • Tumor may extend into superficial fat
  • Numerous histological subtypes (An Bras Dermatol 2014;89:472):
Microscopic (histologic) images

Contributed by Brandon Zelman, D.O. and Jodi Speiser, M.D.
Spindled fibroblasts and epithelioid histiocytes

Spindled fibroblasts and epithelioid histiocytes

Dermal based proliferation Dermal based proliferation

Dermal based proliferation

Dermal proliferation

Dermal proliferation

Whirled appearance

Whirled appearance

Collagen trapping

Collagen trapping


Increased cellularity and collagen trapping

Increased cellularity and collagen trapping

Dermal based proliferation that appears “busy”

Dermal based proliferation that appears busy

 Increased dermal cellularity

Increased dermal cellularity

Spindled fibroblasts and epithelioid histiocytes

Spindled fibroblasts and epithelioid histiocytes

CD34-

CD34-

CD10+

CD10+


Keratin negative

Keratin-

S100-

S100-

SMA weakly expressed

SMA weakly expressed

CD34- CD34-

CD34-

CD10+

CD10+

Virtual slides

Images hosted on other servers:

Dermatofibroma

Positive stains
Negative stains
Videos

Dermatofibroma

Anerysmal fibrous histiocytoma


Cellular dermatofibroma

Lipidized dermatofibroma

Sample pathology report
  • Skin, right arm, excision:
    • Dermatofibroma
  • Skin, left shin, excision:
    • Dermatofibroma (see comment)
    • Comment: Immunohistochemical stains were performed on the above specimen. The cells are positive for factor XIIIa and negative for CD34. This supports the above diagnosis.
Differential diagnosis
Board review style question #1
Which of the following is true of dermatofibromas?

  1. Cellular proliferation involves both the epidermis and dermis
  2. CD34 is positive at the center of the lesion
  3. Collagen trapping is seen at the periphery of the lesion
  4. Deep margins of the lesion typically show extensive infiltration
Board review style answer #1
C. Collagen trapping is seen at the periphery of the lesion

Comment Here

Reference: Dermatofibroma (cutaneous fibrous histiocytoma)
Board review style question #2
Which immunohistochemical profile would be seen in a dermatofibroma?

  1. S100- / CD34- / CD163+ / MART1-
  2. S100- / CD34+ / CD163+ / MART1-
  3. S100+ / CD34- / CD163- / MART1+
  4. S100+ / CD34- / CD163+ / MART1-
  5. S100+ / CD34+ / CD163+ / MART1-
Board review style answer #2
A. S100- / CD34- / CD163+ / MART1-

Comment Here

Reference: Dermatofibroma (cutaneous fibrous histiocytoma)
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