Dermatofibroma

Dermatofibroma – 5 Interesting Facts

1. Most dermatofibromas are round to oval, firm, painless papules or nodules.
2. Patients may report a history of preceding trauma (e.g., insect bites).
3. Dermatofibromas are benign and do not require treatment, but some cases are subject to minor continued trauma, particularly on lesions of the lower legs of women (from shaving).
4. Rare patients with a history of immunosuppression, such as systemic lupus erythematosus or HIV infection, may demonstrate the explosive onset of multiple dermatofibromas.
5. Dermatofibromas will often grow slowly until they reach a particular size and then will remain stable. Some dermatofibromas will regress, typically over years, but sometimes rapidly. Some large dermatofibromas will behave in an aggressive fashion. A few so-called “metastatic” cases have been reported in the literature, but whether these cases represent dermatofibromas or unrecognized sarcomas is debated.

Etiology and Risk Factors

• A dermatofibroma, also known as cutaneous fibrous histiocytoma, is a common tumor of fibrohistiocytic origin. There is debate as to whether dermatofibromas represent a neoplastic or reactive process. In support of the former is the development of lesions at sites of injury (e.g., shaving trauma on the legs, insect bites), but studies of the methylation pattern of the polymorphic X chromosome−linked androgen receptor have demonstrated that dermatofibromas are clonal proliferations, and are probably neoplastic.
• Most dermatofibromas occur in persons 20 to 50 years of age, with a slight female predominance.

Diagnosis

Approach to Diagnosis

• The diagnosis is usually made based on the clinical presentation and clinical appearance.

Workup

History

• Patients may report a history of preceding trauma (e.g., shaving trauma on the legs of women, insect bites).
• Rare patients with a history of immunosuppression, such as systemic lupus erythematosus or HIV infection, may demonstrate the explosive onset of multiple dermatofibromas.

Physical Examination

• Most dermatofibromas occur on the lower extremities but also on the trunk, head, and neck.
• Most dermatofibromas are round to oval, firm, painless papules or nodules. The lesion may be exophytic, dimpled, or flat, with a color that varies from skin-colored to tan to brown to violaceous.
• Rare cases with lipidization may have yellow tones. Occasional cases with abundant hemosiderin may appear dark purple or black (hemosiderotic dermatofibroma).
• With lateral compression, many dermatofibromas will dimple (dimple sign or Fitzpatrick sign).
• Dermatofibromas usually lack overlying scale unless the lesion has been irritated, inflamed, or traumatized.

Diagnostic Procedures

• A deep shave, punch, or incisional or excisional biopsy may be performed on problematic lesions.

Treatment

Approach to Treatment

• Dermatofibromas are benign and do not require treatment, but some cases are subject to minor continued trauma, particularly on lesions of the lower legs of women (from shaving).

Treatment Procedures

• For problematic lesions, extirpation is usually curative. Smaller lesions can be removed with a punch.
• Dermatofibromas of the face, large dermatofibromas (>2 cm), and dermatofibromas in children are more likely to be locally aggressive and should be completely excised, if surgically feasible.

References

1.Hui P, et al. Clonal analysis of cutaneous fibrous histiocytoma (dermatofibroma). Journal of Cutaneous Pathology. 2002;29(7):385-389.

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2.Mentzel T, et al. Benign fibrous histiocytoma (dermatofibroma) of the face: clinicopathologic and immunohistochemical study of 34 cases associated with an aggressive clinical course. The American Journal of Dermatopathology. 2001;23(5):419-426.

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