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- Common benign tumor of the epidermis
- Formed from keratinocytes
- Frequently appears in multiples on the head, neck, and trunk of older individuals but may occur on any hair-bearing area of the body. Lesions spare the palms and soles.
- Typically can present as multiple, well circumscribed, yellow to brown raised lesions that feel greasy, velvety, or warty usually described as having “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
- Rarely seen before 30 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
- 69–100% in patients >50 years of age (1)
- The prevalence rate increases with advancing age.
Etiology and Pathophysiology
- Seborrheic keratoses are monoclonal tumors.
- Etiology still is largely unclear.
- Ultraviolet (UV) light and genetics are 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 (1).
Sun protection methods may help prevent seborrheic keratoses from developing.
Commonly Associated Conditions
- Sign of Leser-Trélat: a paraneoplastic syndrome characterized by a sudden outbreak of multiple seborrheic keratoses in association with an internal malignancy, most commonly adenocarcinoma of the stomach (2). Seborrheic keratosis may resolve with treatment of the malignancy and reappear with neoplasm recurrence (1).
- Documentation of other cutaneous lesions, such as basal cell carcinoma, malignant melanoma, Bowen disease, or squamous cell carcinoma, growing adjacent to or within a seborrheic keratosis, has been reported. The exact relationship between lesions is unclear.