Dermatofibroma

Aka: Dermatofibroma, Solitary histiocytoma, Sclerosing Hemangioma, Nodulus Cutaneous, Fitzpatrick's Sign, Benign Fibrous Histiocytoma

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II. Epidemiology

  1. Males predominate (3:1 ratio)
  2. Age of onset 20-50 years old

III. Pathophysiology

  1. Idiopathic, benign, fibroblast proliferation within the skin

IV. Causes

  1. Idiopathic benign skin tumor
  2. Fibrous reaction to local irritation
    1. Local Trauma
    2. Insect Bite
    3. Viral Infection
    4. Folliculitis
    5. Ruptured cysts
  3. Underlying condition (>15 Dermatofibromas)
    1. Immunocompromised patient
    2. Autoimmune Condition

V. Symptoms

  1. Asymptomatic in most cases
  2. Lesions may be pruritic or tender when irritated
    1. Persistently pruritic or painful lesions may prompt biopsy

VI. Signs

  1. Characteristics
    1. Small firm, raised Papule, Plaque or Nodule (3-10 mm)
    2. Lesions develop over months and persist for years
    3. Completely symmetric and regular
    4. Tan or light brown surface (may be red or yellow)
      1. Color is darker at center and gradually fades into normal Skin Color
    5. Fitzpatrick's Sign
      1. Skin dimples downward when compression is applied to lateral margin
      2. Pinching lesion between fingers may best demonstrate dimpling
  2. Distribution
    1. Most common: Anterior thighs and Legs
    2. Moderately common: Arms and Trunk
    3. Uncommon: Head, Palms, and Soles
  3. Variants
    1. Multiple eruptive lesions
      1. Seen in 0.3% of cases (typically Immunocompromised: HIV, SLE)
      2. More than 15 Dermatofibromas are otherwise rare aside from this condition
    2. Dermatofibrosarcoma Protuberans
      1. Deep invasion with metastases

VII. Differential Diagnosis

  1. Primary Malignant Melanoma
  2. Scar
  3. Blue Nevus
  4. Pilar Cyst
  5. Metastatic Carcinoma
  6. Kaposi's Sarcoma

VIII. Management

  1. Excision Indications
    1. Repeated Trauma with bleeding, irritation
    2. Unacceptable cosmetic appearance
    3. Uncertain diagnosis (changes in size, color)
  2. Techniques
    1. Eliptical excision or Punch Biopsy
      1. Risk of scarring
      2. Preferred for better histology if malignancy or atypical lesions are suspected
    2. Other methods (incomplete removal)
      1. Laser ablation (may be preferred)
      2. Shave Biopsy
      3. Cryotherapy

IX. References

  1. Fitzpatrick (1999) Color Atlas Dermatology
  2. Higgins (2015) Am Fam Physician 92(7): 601-7 [PubMed]
  3. Wagner (2024) Am Fam Physician 110(4): 353-61 [PubMed]

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