Keratosis, Seborrheic

BASICS

DESCRIPTION

  • Common benign tumor of the epidermis formed from proliferation of keratinocytes
  • Frequently appears in multiples on the head, neck, and trunk (sparing the palms and soles) of older individuals but may occur on any hair-bearing area of the body
  • Typically presents as multiple, well-circumscribed, yellow to brown raised lesions that feel greasy, velvety, or warty; usually described as having a “stuck-on” appearance
  • Clinical variants include the following:
    • Common seborrheic keratosis
    • Dermatosis papulosa nigra
    • Stucco keratosis
    • Flat seborrheic keratosis
    • Pedunculated seborrheic keratosis
  • Synonym(s): SK, verruca seborrhoica; seborrheic wart; senile wart; basal cell papilloma; verruca senilis; benign acanthokeratoma; barnacles of aging

EPIDEMIOLOGY

Incidence

  • Predominant age: appear most commonly in those aged 31 to 50 years, and incidence increases with age, peaking at age 60 years
  • Predominant sex: slightly more common and more extensive involvement in males
  • Most common among Caucasians, except for the dermatosis papulosa nigra variant, which usually presents in darker skinned individuals

Prevalence

  • 69–100% in patients >50 years of age
  • The prevalence rate increases with advancing age.

ETIOLOGY AND PATHOPHYSIOLOGY

  • Etiology remains largely unclear with ultraviolet (UV) light and genetics thought to be involved.
  • The role of human papillomavirus is uncertain.

Genetics

An autosomal dominant inheritance pattern is suggested.

RISK FACTORS

  • Advanced age
  • Exposure to UV light and genetic predisposition are the possible factors.

GENERAL PREVENTION

Sun protection methods may help prevent seborrheic keratoses from developing.

COMMONLY ASSOCIATED CONDITIONS

  • Sign of Leser-Trélat: a paraneoplastic syndrome characterized by a rapid outbreak of multiple seborrheic keratoses often associated with an internal malignancy, most commonly adenocarcinoma; seborrheic keratosis may resolve with treatment of the malignancy and reappear with neoplasm recurrence.
  • Documentation of other cutaneous lesions, such as basal cell carcinoma, malignant melanoma, or squamous cell carcinoma, growing adjacent to or within a seborrheic keratosis, has been reported. The exact relationship between lesions is unclear.

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