Dermatofibroma (Benign Fibrous Histiocytoma)

Dermatofibroma (Benign Fibrous Histiocytoma)

David S. Cassarino, MD, PhD

Classic dermatofibroma shows a dermal-based proliferation of bland spindled to histiocytic-appearing cells, associated with a Grenz zone and overlying epidermal hyperplasia and basilar pigmentation.

Higher power examination of a classic dermatofibroma shows a proliferation of bland spindled to histiocytoid cells entrapping numerous hyalinized balls of collagen image.



  • Dermatofibroma (DF)

  • Fibrous histiocytoma (FH)


  • Cutaneous fibrous histiocytoma

  • Sclerosing hemangioma

  • Histiocytoma

  • Epithelioid cell histiocytoma


  • Common, benign, limited proliferation of mesenchymal cells in dermis

  • Lineage not well defined, although commonly referred to as “fibrohistiocytic”



  • Evidence supports both reactive and neoplastic pathogenesis

    • Histiocytic population may be clonal; fibroblast/myofibroblastic population may be polyclonal (reactive)

  • Tumor may be preceded by local trauma, including insect bite in some cases

    • However, often no inciting event identified



  • Incidence

    • Common tumors in most populations

  • Age

    • All ages, but most common in 4th and 5th decades

  • Gender

    • Affects males and females equally


  • Typically occur on distal extremities but may present at any cutaneous site


  • Firm, isolated, flesh-colored subcutaneous papule or nodule

    • New DFs are typically pink (vascular); older DFs are brown (overlying melanocyte hyperplasia)

  • Multiple DFs occur in immunosuppressed populations

  • “Dimpling” sign when in vivo DF is pinched by fingers


  • Excision usually curative


  • Excellent in vast majority of cases

    • Local recurrence potential significant (up to 30%) with cellular variant

    • Metastasis and death from some cellular and atypical tumors reported

      • Usually large and deep lesions


General Features

  • Firm, circumscribed but nonencapsulated, dermalbased tumor

  • White to yellow cut surface

  • Can have cystic changes and hemorrhage


Histologic Features

  • Dermal-based proliferation of typically bland spindled to histiocytic-appearing cells

    • Either spindled (fibroblastic) or histiocytoid cells may predominate

    • Early lesions typically show more histiocytes and lymphocytes

    • Established lesions show greater cellularity and spindled cells

    • Older lesions show more fibrosis

    • Spindled cells show elongated eosinophilic cytoplasmic processes

    • “Histiocytic” type cells are larger, epithelioid-shaped, and have abundant pale vacuolated cytoplasm

    • Cytologic atypia and pleomorphism are usually minimal

  • Tumors are grossly circumscribed but microscopically have irregular, often jagged borders

  • Collagen trapping at periphery

    • Spheres of intensely eosinophilic collagen (socalled “collagen balls”) separated by bands of pale fibrohistiocytic cells

  • Grenz zone

    • Tumor often spares band of superficial dermis

  • Folliculosebaceous induction and basilar epidermal hyperplasia overlying DF

    • Can mimic basal cell carcinoma if basilar induction is marked

  • Adjacent adnexal hyperplasia

  • Overlying melanocyte hyperplasia occasionally seen

    • So-called “dirty sock” sign

Predominant Pattern/Injury Type

  • Ill-defined borders

  • Nodular proliferation

  • Fibrous

  • Histiocytic

Predominant Cell/Compartment Type

  • “Fibrohistiocytic”

Histologic Subtypes

Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Dermatofibroma (Benign Fibrous Histiocytoma)

Full access? Get Clinical Tree

Get Clinical Tree app for offline access
%d bloggers like this: