AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

Dermatofibroma (DF) is a common cutaneous nodule of unknown etiology that occurs more often in women. The lesion frequently develops on the extremities (mostly the lower legs) and is usually asymptomatic, although pruritus and tenderness are not uncommon. The latter feature is seen in a sufficient number of patients to make DF the most prevalent of all painful skin tumors. A number of well-described, histologic subtypes have been reported. Removal of the tumor is not necessary unless diagnostic uncertainty exists or particularly troubling symptoms are present.

Pathophysiology

The precise mechanism for the development of DF is unknown. Rather than a reactive tissue change, DF seems more likely to be a neoplastic process because of the persistent nature of the lesion and the demonstration that it is a clonal proliferative growth.¹ Clonality, of course, by itself, is not necessarily synonymous with a neoplastic process; it has been demonstrated in inflammatory conditions, including atopic dermatitis, lichen sclerosis, and psoriasis.

Immunohistochemical testing with antibodies to factor XIIIa is frequently positive in DF, while antibodies to MAC 387 show less consistent results. The former antibody labels fibroblasts (dermal dendrocytes), while the latter labels monocyte-derived macrophages (histiocytes). Controversy exists as to whether the factor XIIIa positivity occurs within the actual tumor cells of DF or simply labels the reactive stromal cells; hence, the cell of origin for the spindle cell proliferation of DF is debatable. The cell surface proteoglycan, syndecan-1, may play a role in the growth of DF.² Transforming growth factor-beta signaling might be a trigger of the fibrosis seen in DF.³

Frequency

United States

DF is relatively common.

International

Incidence is probably similar to that in the United States.

Mortality/Morbidity

DF is regarded as a benign lesion; however, discomfort from pain or itching may be significant. The few case reports of metastatic DF are disputable from the standpoint of histologic diagnosis. Such reported lesions were highly cellular, of large size, and locally recurrent.⁴ Indolent pulmonary metastases also were observed.

Race

Frequency appears to be similar in all races.

Sex

Females are affected more commonly than males, with a male-to-female ratio of 1:4.

Age

DF can occur in patients of any age, but it usually develops in young adulthood. Approximately 20% of the lesions occur before age 17 years.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

History

DFs typically arise slowly and most often occur as a solitary nodule on an extremity, particularly the lower leg, but any cutaneous site is possible. Several lesions may be present, but only rarely are multiple (ie, 15 or more) tumors found. This multiple variant is seen most frequently in the setting of autoimmune disease or altered immunity, such as systemic lupus erythematosus, HIV infection, or leukemia and may be indicative of worsening immunoreactivity. Mild regression has been reported with clinical improvement of the underlying disorder. Conversely, drugs to treat the underlying disorders have also been implicated in causation. Multiple clustered DFs also have been reported.⁵ Patients may describe a hard mole or unusual scar and may be concerned about the possibility of skin cancer.

DFs are characteristically asymptomatic, but itching and pain often are noted. They are the most common of all painful skin tumors.⁶ Women who shave their legs may be bothered by the razor traumatizing the lesion in that region, causing pain, bleeding, erosive changes, and ulceration. Although cases of unusually rapid growth exist, most DFs remain static for decades or persist indefinitely. Uncommon reports describe spontaneous regression,⁷ and this may yield postinflammatory hypopigmentation.

Physical

Typically, the clinical appearance is a solitary, 0.5- to 1-cm nodule. A sizable minority of patients may have several lesions, but rarely are more than 15 lesions present. The overlying skin can range from flesh to gray, yellow, orange, pink, red, purple, blue, brown, or black, or a combination of hues (see Media File 1). On palpation, the hard nodule may feel like a frozen pea or a small pebble fixed to the skin surface and is freely movable over the subcutis. Tenderness may be elicited with manipulation of the lesion.

The characteristic tethering of the overlying epidermis to the underlying lesion with lateral compression, called the dimple sign, may be a useful clinical sign for diagnosis.⁸ The dimple sign is not unique to DF, and dermatoscopy may be useful in supporting the clinical impression.⁹

The extremities are the most common sites of involvement, particularly the lower legs. Although any cutaneous site can be seen, palm and sole involvement is rare. Giant (>5 cm in diameter), atrophic, atypical polypoid and DF with satellitosis variants have been reported.

Causes

Historically attributed to some traumatic insult to the skin (eg, arthropod bite), the cause of DF is unknown. Because of its persistent nature, DF is probably better categorized as a neoplastic process rather than a reactive tissue change. A study of eruptive DFs in a kindred suggests that a genetic component may exist.¹⁰

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Other Problems to be Considered

Cutaneous chondroma
Desmoplastic trichoepithelioma
Foreign body granuloma
Granular cell tumor
Nodular fasciitis
Nodular scabies
Sclerosing sweat duct carcinoma

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Procedures

• For those trained in dermoscopy, this may be a useful adjunctive diagnostic technique. The most common pattern seen is a peripheral pigment network with a central white area.¹¹ If a suspicious melanocytic pattern is noted with dermoscopy, a diagnostic biopsy is warranted. Also see Dermoscopy.
• If any diagnostic uncertainty exists, excisional biopsy with removal of the subcutaneous fat should be performed.

Histologic Findings

The overlying epidermis is usually acanthotic. Pseudoepitheliomatous hyperplasia and a basaloid proliferation may be noted. Basal cell carcinomas occurring upon a DF have been reported. Increased pigment may be seen, which may be iron or melanin. Most lesions display a grenz zone of normal papillary dermis overlying the tumor.

The bulk of the tumor is within the mid dermis where no capsule is present and the periphery of the lesion blends with the surrounding tissue. Whorling fascicles of a spindle cell proliferation with excessive collagen deposition are characteristic. At the periphery, the spindle cells characteristically wrap around normal collagen bundles (see Media Files 2-3).

The subcutis typically is preserved, but if involved (especially when a storiform [cartwheel] pattern is observed), be alert to the possibility of the lesion being a dermatofibrosarcoma protuberans (DFSP). Antibodies toward factor XIIIa and CD34 may be useful in distinguishing the 2 tumors, with the former suggesting DF and the latter suggesting DFSP.¹² Stromelysin-3 expression of DF by immunohistochemical staining may also be useful in distinguishing between the two.¹³ Indeterminate cases of tumors that share histologic and immunohistochemical features of both DF and DFSP have been described.¹⁴ Transforming growth factor-beta type I and type II receptor expression patterns may also help distinguish between DF and DFSP.³

As far as location, 2 variants have been reported relatively frequently on the hands and feet. One shows schwannomalike features with lamellar and storiform fibrosis and a palisading of fibroblasts. The other is a myxoid variant, which appears to localize to the fingers and toes and is thought to share an association with mucous cyst of the finger.

One clinicopathologic classification scheme¹⁵ describes the following 4 categories of DF: (1) those with architectural peculiarities, such as deep penetrating, atrophic, giant, aneurysmal (angiomatoid), hemangiopericytomalike, palisading, or ossifying variants; (2) cellular/stromal DFs, such as clear cell, granular cell, myofibroblastic, sclerotic, monster cell, atypical (pseudosarcomatous), elusive (hemosiderotic), cholesterotic (lipidized), and myxoid variants; (3) DFs with architectural and cellular/stromal changes in homogeneous arrangement, including epithelioid cell, cellular benign, smooth muscle proliferative, basal cell carcinoma–like, pseudolymphomatous, multinucleate cell angiohistiocytoma, cellular neurothekeoma, plexiform fibrohistiocytic tumor, plexiform xanthoma, and plexiform xanthomatous tumor subtypes; and (4) a complex, composite or combined DF category with 2 or more architectural and cellular/stromal patterns in a single lesion.

Of the variants listed above, keep in mind that the uncommon sclerotic fibromalike dermatofibroma should be differentiated from sclerotic fibroma. A 2005 study¹⁶ showed 7 of 7 of the former lesions to be negative for CD34 and CD99, while 3 of 3 solitary fibromas were positive for CD34 and CD99. For comparison, 14 of 14 "common-type" dermatofibromas in this study were negative for CD34, while 4 demonstrated positivity with CD99.

Lichenoid DF, ulcerated DF, erosive DF, diffuse eosinophilic infiltrate DF, DF accompanied by perforating dermatosis, and DF with overlying sebaceous hyperplasia have also been reported.

A 2005 series¹⁷ reported the uncommon occurrence of dermatofibroma and melanocytic lesions in the same biopsy specimen. Four of 14 specimens showed the 2 processes to seemingly merge imperceptibly. The lesions included junctional, dermal, and compound nevi as well as a single case of melanoma in situ. Knowledge of this relationship can help prevent rendering the wrong diagnosis and is facilitated by the use of immunohistochemistry, with the melanocytic lesions showing S-100 and Mart-1 positivity with FXIIIa negativity and the dermatofibroma showing S-100 and Mart-1 negativity and FXIIIa positivity. A subsequent case report¹⁸ documenting an invasive melanoma occurring in association with a DF underscores the role of these immunohistochemical stains.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical Care

No treatment is usually necessary. Simple reassurance that the lesion is benign may be indicated. Intralesional steroid injections have been attempted with variable results.

Surgical Care

For cosmetically unacceptable lesions or lesions that are particularly symptomatic, or if any diagnostic uncertainty exists, complete excision, including the subcutaneous fat, is the ideal procedure. An inverted pyramidal biopsy technique may allow for an aesthetically pleasing result, while still providing adequate tissue for histologic findings.¹⁹ Superficially shaving the lesion or cryosurgery can be attempted for cosmesis or to decrease the symptoms; however, recurrences are more likely. Carbon dioxide laser treatment of multiple facial DF has been reported.²⁰

The Medscape Dermatologic Surgery Resource Center may be helpful.

FOLLOW-UP

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Further Outpatient Care

• If the lesion is not removed and significant change occurs in the color, size, border, or symptoms, the patient should seek follow-up evaluation.
• If complete removal has been attempted, patients with lesions that recur should seek follow-up evaluation.
• If multiple (ie, 15 or more) lesions develop, screening for autoimmune disease or altered immunity is indicated.

Prognosis

• DF is considered a benign lesion, and the prognosis for patients with this condition is excellent. Reports of metastatic DF are extremely rare, and the histologic diagnosis in those cases is disputable.

Patient Education

• For excellent patient education resources, visit eMedicine's Procedures Center. Also, see eMedicine's patient education article Mole Removal.

MISCELLANEOUS

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• All specimens that are removed should be submitted for histologic confirmation of the diagnosis of DF.
• A false-negative diagnosis of melanoma is the top reason for a malpractice claim against pathologists. In such cases, one of the common incorrect microscopic diagnoses is dermatofibroma.

MULTIMEDIA

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  Erythematous, slightly hyperpigmented nodule on the leg. Courtesy of David Barnette, MD.
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Media type:  Photo

Media file 2:  Acanthotic epithelium with basilar hyperpigmentation (dirty feet) over a dermal spindle cell proliferation (X10). Courtesy of David Barnette, MD.
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Media type:  Photo

Media file 3:  Collagen trapping by the dermal fibrohistiocytic infiltrate (X40). Courtesy of David Barnette, MD.
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Media type:  Photo

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

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23. Aydin E, Vardareli OS, Bilezikçi B, Ozgirgin ON. [Dermatofibroma accompanied by perforating dermatosis in the auricle: a case report]. Kulak Burun Bogaz Ihtis Derg. 2005;15(3-4):83-6. [Medline].
24. Curcó N, Jucglà A, Bordas X, Moreno A. Dermatofibroma with spreading satellitosis. J Am Acad Dermatol. Dec 1992;27(6 Pt 1):1017-9. [Medline].
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32. Shinojima Y, Hara H, Shimojima H, Terui T. Cutaneous chondroma with overlying pigmentation clinically mimicking dermatofibroma. Br J Dermatol. Jan 2006;154(1):178-81. [Medline].
33. Sánchez Yus E, Soria L, de Eusebio E, Requena L. Lichenoid, erosive and ulcerated dermatofibromas. Three additional clinico-pathologic variants. J Cutan Pathol. Mar 2000;27(3):112-7. [Medline].
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35. Wick MR, Ritter JH, Lind AC, Swanson PE. The pathological distinction between "deep penetrating" dermatofibroma and dermatofibrosarcoma protuberans. Semin Cutan Med Surg. Mar 1999;18(1):91-8. [Medline].
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Article Last Updated: May 22, 2008