Seborrheic keratosis (SK) is one of the most common benign skin growths, especially as people age. These growths are non-cancerous and are sometimes referred to as “wisdom spots” because of their association with older adulthood. When these lesions are removed, a frequent concern is whether the same spot will grow back. Understanding the nature of the growth and the specific removal techniques helps clarify the likelihood of a lesion returning versus the emergence of new ones.
Understanding Seborrheic Keratosis
Seborrheic keratoses originate from the benign proliferation of keratinocytes, the main cells in the skin’s outermost layer (epidermis). These lesions are commonly described as having a “stuck-on” or waxy appearance. Their color can vary widely, ranging from light tan or yellow to dark brown or nearly black.
They typically start as small, flat spots and gradually become thicker and more raised, often developing a rough or scaly surface texture. While they can appear almost anywhere on the body, they are most frequently observed on the chest, back, face, and scalp. The development of SK is strongly influenced by genetics, increasing age, and sun exposure, but they are not contagious or caused by an infection.
Common Removal Techniques
Removal of seborrheic keratoses is typically performed for cosmetic reasons or because the lesion is irritated by clothing. Procedures are designed to be minimally invasive, focusing only on the superficial layers of the skin where the growth resides. The intent is to destroy the keratinocyte cells at the base of the lesion without causing significant damage to the deeper dermis layer.
One of the most common methods is cryotherapy, which involves applying liquid nitrogen to the growth, causing the cells to freeze and die. The treated lesion then forms a scab and falls off, though this method may carry a risk of temporary or permanent lightening of the skin. Another technique is shave excision, where the lesion is carefully shaved off the skin surface using a specialized blade after local numbing.
Electrodesiccation, often combined with curettage, is a standard approach, particularly for thicker growths. This method uses a targeted electrical current to burn and destroy the tissue, which is then scraped away with a surgical instrument called a curette.
Does the Same Lesion Return?
The specific seborrheic keratosis lesion that was completely treated will generally not return after a successful removal procedure. When a dermatologist successfully destroys the entire lesion, including the basal layer of the abnormal cells, the growth is permanently eradicated. The low recurrence rate of an individual lesion confirms the effectiveness of modern removal techniques.
However, if the removal is incomplete, the growth can regrow at the original site due to residual cells. This regrowth is a recurrence of the original lesion, not a new one. Recurrence rates are relatively low, with studies suggesting that approximately 10 to 15% of treated lesions may show some regrowth within five years. For instance, cryotherapy often has recurrence rates below 10%.
Why New Lesions Still Appear
While the treated lesion site is unlikely to see a return of the original growth, it is common for individuals to develop new seborrheic keratoses in different locations. This occurs because the underlying predisposition that caused the initial growth is not changed by the removal of a single lesion. Having SKs indicates a genetic or age-related susceptibility to forming these benign skin tumors over time.
The removal of one or more growths does not alter the biological tendency of the skin in other areas to develop new lesions. Therefore, people who have had one SK removed should expect that new ones may appear elsewhere on the body as they continue to age.
In a few instances, a sudden eruption of numerous new seborrheic keratoses may occur, known as the sign of Leser-Trélat. Though this sign is rare, it can suggest an underlying internal malignancy, such as gastrointestinal cancer. The abrupt appearance of many new growths, especially if they are itchy or accompanied by other symptoms, warrants an immediate medical evaluation. For the vast majority of people, new SKs are simply an ongoing manifestation of a common, harmless aging process.