Seborrheic keratosis
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Seborrheic keratosis (lat. keratosis seborrhoica) is a benign, non-cancerous epidermal lesion resulting from excessive proliferation (growth) of basal epidermal cells. It is one of the most common skin lesions in adults, and in the population over 50 years of age, it may occur in more than 80% of individuals. This lesion does not have malignant potential, but it is often mistaken for melanoma or basal cell carcinoma of the skin. Therefore, any new, rapidly growing, or changing pigmented lesion requires dermatological evaluation and, if there is any doubt, dermatoscopic or histopathological examination.
Seborrheic keratosis – causes
The etiology of seborrheic keratosis is not fully understood. It is considered to be primarily an age-related and genetically predisposed change, rather than being associated with excessive sebum production, despite the name.
The most important predisposing factors include:
- Age – the frequency increases with age; they are rarely observed before the age of 30.
- Family predisposition – numerous lesions can run in families.
- Genetic factors – molecular studies have shown mutations, including in the FGFR3 and PIK3CA genes, leading to uncontrolled proliferation of keratinocytes.
- UV radiation – sun exposure can promote the appearance of lesions, especially on the face and décolleté.
It is important to emphasize that:
- the lesion is not contagious,
- does not result from "skin contamination" or improper care,
- does not transform into melanoma.
The sudden, numerous appearance of seborrheic keratoses (known as the Leser-Trélat sign) may, although rarely, be a marker of internal organ cancer, particularly of the gastrointestinal tract. In such a situation, further internal diagnostic evaluation is recommended.
Seborrheic Keratosis – What It Looks Like
The clinical appearance of a seborrheic keratosis is quite characteristic, although the lesions can exhibit significant morphological variability.
Typical features:
- Color: ranges from light brown to dark brown, and almost black; less commonly yellowish.
- Surface: rough, verrucous, "waxy".
- Consistency: soft or slightly firm.
- Margins: clearly demarcated from the surrounding skin.
- Clinical impression: the lesion gives the impression of being "stuck on" the skin.
Location:
- trunk (especially the back),
- face,
- scalp,
- décolleté.
It usually does not cause pain. However, it may:
- itch,
- become irritated by clothing,
- bleed after mechanical trauma.
In differential diagnosis, the following should be considered:
- melanoma,
- basal cell carcinoma,
- viral wart,
- pigmented nevus.
Dermatoscopy allows visualization of characteristic structures, such as horn cysts or pseudo-hair follicle openings, which facilitate distinguishing the lesion from malignant tumors. In ambiguous cases, excision of the lesion and histopathological examination are performed.
Seborrheic Keratosis - Removal
Removal of a seborrheic keratosis is not medically necessary if the lesion does not raise oncological suspicions. The most common indications for the procedure are:
- aesthetic reasons,
- chronic irritation of the lesion,
- recurrent bleeding,
- diagnostic uncertainty.
Removal methods include:
1. Laser therapy (e.g., CO₂ laser)
- precise vaporization of the lesion,
- minimal damage to surrounding tissues,
- short healing time.
2. Cryotherapy (liquid nitrogen)
- controlled freezing of the lesion,
- possible temporary skin discoloration.
3. Electrocautery / curettage
- mechanical removal of the lesion with vessel coagulation,
- used for elevated lesions.
4. Surgical excision
- recommended if cancer is suspected,
- allows for complete histopathological examination.
In clinical settings such as Ambasada Urody Clinic & Spa in Warsaw, the removal of skin lesions is performed following prior medical qualification and dermatoscopic evaluation. In the case of atypical lesions, the material is sent for histopathological examination.
Post-procedure recommendations include:
- avoiding sun exposure for a minimum of 4 weeks,
- using SPF 50+ photoprotection,
- local care with products supporting epidermal regeneration.
