• See Also
  1. Linear Dermatitis
  2. Common Pediatric Skin Rashes
  • Epidemiology
  1. Onset Age 5 months to 5 years
  • Pathophysiology
  1. Unilateral distribution following Blaschko Lines
    1. Developmental pathways of epidermal cell migration and proliferation in the fetus
  2. Unclear cause
    1. T-Cell Mediated dermatosis
    2. Epigenetic mosaicism may contribute (different cell populations with different Genotypes)
  3. Possible Triggers
    1. Viral Infection
    2. Autoimmune Conditions
    3. Pregnancy
    4. Environmental factors
  • Findings
  1. Unilateral Linear Dermatitis along Blaschko Lines (see pathophysiology above)
    1. Typically affects extremities (rarely on Fingernails)
    2. May affect trunk
  2. Asymptomatic flesh-colored, flat topped Papules
    1. Lesions may be pruritic
    2. Erythematous Papules may be more difficult to visualize in darker skin
  3. Course
    1. Skin lesions may persist for 1-2 years
    2. Possible longer-standing skin pigmentation changes
  • Differential Diagnosis
  1. See Linear Dermatitis
  • Labs
  1. Clinical diagnosis (does not require biopsy)
  2. Biopsy findings (if performed)
    1. Lymphocytic inflammatory infiltrate of Macrophages and Lymphocytes
    2. Surrounds Eccrine Glands, Hair Follicles, vessels
  • Management
  1. No treatment needed
  2. Mild Pruritus may be treated symptomatically
    1. Topical skin Emollients
    2. Low potency Topical Corticosteroids (7-10 days)
  3. Reassurance that lesions are benign and resolve spontaneously after 1-2 years without treatment
    1. Chronic skin pigmentation changes may persist
  • References
  1. Gallagher (2025) Am Fam Physician 111(2): 179-80 [PubMed]
  2. Leung (2024) Curr Pediatr Rev +PMID: 38279714 [PubMed]