- 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
- System(s) affected: integumentary
- Synonym(s): SK, verruca seborrhoica; seborrheic wart; senile wart; basal cell papilloma; verruca senilis; basal cell acanthoma; benign acanthokeratoma; barnacles of aging
- Predominant age: appear most commonly in those aged 31 to 50, and incidence increases with age, peaking at age 60 (1)
- 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
- 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.
An autosomal dominant inheritance pattern is suggested.
- Advanced age
- Exposure to UV light and genetic predisposition are possible factors.
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 (2). 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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