What are the risk factors for seborrheic keratosis?

Risk Factors for Seborrheic Keratosis

The primary risk factors for seborrheic keratosis include advanced age, genetic predisposition, ultraviolet radiation exposure, and certain systemic conditions such as immunosuppression. 1, 2, 3

Key Risk Factors

Age-Related Factors

• Advanced age: Most significant risk factor, with prevalence increasing dramatically after age 50 1
• Rare in adolescents and young adults, but can occasionally occur 2

Genetic Factors

• Genetic predisposition: Family history plays a significant role 1
• Multiple genetic mutations have been identified:
  • Fibroblast growth factor receptor 3 (FGFR-3) mutations 2
  • FOXN1 gene mutations 2

Environmental Factors

• Ultraviolet (UV) radiation exposure: Contributes to development through:
  • Alteration of biochemical concentrations
  • Changes in expression of factors like glutamine deaminases, endothelin, and stem cell factor 2
• Sun-exposed areas: Higher prevalence on face and upper trunk 1

Immunological Factors

• Immunosuppression: Significantly increases risk, particularly:
  • Transplant-associated immunosuppression (10% vs 0% in controls) 4
  • General immunosuppression (19% vs 3% in controls) 4

Associated Medical Conditions

• Viral infections:
  • Human papillomavirus (HPV) - particularly in genital lesions 2
  • Merkel cell polyomavirus has been detected in some lesions 2
• Paraneoplastic phenomenon:
  • Eruptive seborrheic keratoses can occur as Leser-Trélat sign (paraneoplastic condition) 3
  • Pseudo-Leser-Trélat sign can develop with certain targeted cancer treatments 3

Demographic Patterns

• Gender: Male preponderance reported 2
• Ethnicity:
  • Common seborrheic keratoses are more frequent in Caucasians
  • Dermatosis papulosa nigra (a variant) is more prevalent in individuals with Fitzpatrick skin type 3 or higher 3

Clinical Considerations

Distribution Patterns

• Can occur on all body sites except palms and soles 1
• Most commonly found on:
  • Face
  • Upper trunk
  • Sun-exposed areas

Pathophysiological Mechanisms

• Accumulation of amyloid-associated proteins 2
• Extrinsic skin aging appears linked to occurrence 3
• Multiple oncogenic mutations have been identified 2

Malignant Potential

• Generally considered benign with no malignant potential despite FGFR-3 mutations 3
• Rare cases of squamous cell carcinoma arising within seborrheic keratosis (SCC-SK) have been reported:
  • More common in elderly men with history of immunosuppression
  • Particularly associated with organ transplants 4

Understanding these risk factors can help with early identification and appropriate management of seborrheic keratosis, particularly in high-risk populations such as elderly individuals and those who are immunosuppressed.