Seborrhoeic keratoses are benign but often unwanted — and sometimes difficult to distinguish from more worrying lesions without expert assessment. Here is what you need to know.
Seborrhoeic keratoses — sometimes called seborrhoeic warts or basal cell papillomas — are among the most common skin lesions in adults over 40. By the age of 70, the majority of people have at least one, and many have dozens. They are completely benign. But they are also frequently mistaken for melanoma, and melanoma can occasionally be mistaken for them.
At Lambert Medical Practice, Dr Nancy Abdelrahman assesses and treats seborrhoeic keratoses with dermoscopy (allowing confirmation of the diagnosis with high accuracy) and cryotherapy (for removal of lesions that are symptomatic, changing, or cosmetically unwanted). This guide explains what seborrhoeic keratoses are, when to have them checked, and whether removal is appropriate for you.
Seborrhoeic keratoses are benign epidermal growths — overgrowths of skin cells that form raised, warty, rough-surfaced plaques. Despite the name, they have nothing to do with sebaceous glands or oil, and are not caused by sebum production. The term is a misnomer that has persisted in clinical use.
They typically develop from the age of 40 onwards and become more numerous with age. They affect men and women equally, and can appear on any part of the body except the palms, soles and mucous membranes. They are most commonly found on the trunk (chest, back, abdomen), face, shoulders and neck.
Seborrhoeic keratoses have a characteristic appearance — described as looking "stuck on" to the skin, like a barnacle. Features include:
This is the key clinical question — and it is not always straightforward. Seborrhoeic keratoses and melanoma can share features that cause confusion to both patients and clinicians:
| Feature | Seborrhoeic Keratosis | Melanoma |
|---|---|---|
| Colour variation | Multiple browns, can be very dark | Multiple colours — brown, black, blue-grey, red, white |
| Border | Well-defined, can be irregular | Often irregular, notched or blurred |
| Surface | Rough, warty, "stuck on" feel | Usually smooth or nodular |
| Change over time | Slow and gradual if at all | Often rapid change in weeks to months |
| Dermoscopy | Milia cysts, comedo-like openings, fissures — specific SK features | Atypical network, regression, blue-black areas |
| Bleeding | Unusual (may occur with trauma/friction) | Spontaneous bleeding is concerning |
The critical point is that dermoscopy substantially increases diagnostic accuracy for both seborrhoeic keratosis and melanoma. A clinical assessment without dermoscopy is less reliable. If you have a pigmented lesion you are unsure about, dermoscopy by a trained clinician is the appropriate investigation — not a visual inspection alone.
Get a lesion assessed promptly if it has:
Leser-Trélat sign is a rare but important clinical phenomenon — the sudden eruption of large numbers of seborrhoeic keratoses, or a rapid increase in their size and number, can be a paraneoplastic sign associated with internal malignancy. The malignancies most commonly associated include gastric, colorectal, breast and lymphoma.
It is important to emphasise that the vast majority of seborrhoeic keratoses are entirely unrelated to any internal cancer, and simply acquiring more seborrhoeic keratoses with age is normal. Leser-Trélat sign is defined by a sudden, rapid, unexplained eruption — not gradual accumulation over years. If you notice this pattern, see a doctor promptly.
Seborrhoeic keratoses do not need to be removed for medical reasons — they are benign and do not become malignant. The decision to remove one is therefore about symptoms and preference. Common reasons patients choose removal include:
NHS removal of seborrhoeic keratoses for cosmetic reasons is not funded in England, Wales or Scotland. Private dermatology is therefore the route for most patients. At Lambert Medical Practice, the initial consultation includes dermoscopy assessment — confirming the diagnosis — before any removal is planned.
Cryotherapy — the application of liquid nitrogen — is the most commonly used treatment for seborrhoeic keratoses in a primary care dermatology setting. It is fast, effective and leaves minimal scarring for most lesions.
At your appointment, Dr Nancy applies liquid nitrogen using a cryotherapy spray gun or cotton bud to the lesion for a controlled freeze duration (typically 5–20 seconds depending on lesion size and thickness). The lesion turns white immediately, then red and swollen over the following hours. A blister may form over 24–48 hours; the lesion then scabs and falls off over 1–4 weeks.
Larger or thicker seborrhoeic keratoses may require 2–3 treatment sessions spaced 4–6 weeks apart. Very large lesions may alternatively be treated by curettage (scraping under local anaesthetic) or electrocautery, which Dr Nancy will discuss with you at consultation.
Dermoscopy-confirmed diagnosis and cryotherapy removal if appropriate. Dr Nancy Abdelrahman at Lambert Medical Practice — no referral, same-week appointments.
Also at Lambert Medical: Dermatology service page · Seborrhoeic keratosis service page · Dermatologist Surbiton — mole checks and cryotherapy