Seborrheic keratosis (SK) is a common, non-cancerous skin growth that typically appears in mid-adulthood and increases in frequency with age. These lesions are benign epidermal tumors—clusters of extra cells in the outer layer of the skin. SKs are harmless, not contagious, and do not pose a risk for developing skin cancer. Because they sometimes have a crusty or loosely attached look, many people wonder if the growth might simply fall off on its own.
The Appearance and Growth of Seborrheic Keratosis
Seborrheic keratoses are characterized by a distinct “stuck-on” appearance, often described as looking like a barnacle or dripped candle wax. They are raised, round or oval, and range in size up to more than one inch across. The color is highly variable, commonly presenting as tan, brown, or black, but sometimes they can be yellow, white, or gray. The texture is typically waxy, scaly, or rough, sometimes developing a crumbly surface layer due to the buildup of keratin, the fibrous protein found in fingernails. SKs can develop anywhere except the palms and soles, but are most frequently found on the face, chest, back, and scalp. They grow slowly and increase in thickness over time.
Spontaneous Resolution of SK Lesions
Complete, permanent spontaneous resolution of seborrheic keratosis is rare. Although the growths are not deeply rooted, the entire lesion, including the base, typically remains firmly attached to the skin. The flaky or crusty outer layer may occasionally rub off due to friction or accidental scratching, making the lesion appear smaller temporarily. However, the underlying cluster of cells remains and will regrow the superficial layer.
Attempting to pick, scratch, or forcibly remove an SK is discouraged. Manipulating the growth can lead to irritation, localized bleeding, and increase the risk of infection. Furthermore, self-removal increases the likelihood of noticeable scarring compared to professional techniques. Since the base is not fully detached, the growth will almost certainly return after any attempted self-removal.
Clinical Removal Procedures
Professional removal is a common choice because SKs do not fall off completely and can become irritated or cosmetically bothersome. Dermatologists use several safe, in-office procedures, often performed after numbing the area with a local anesthetic. The method chosen depends on the lesion’s size, thickness, and location.
Cryotherapy
Cryotherapy is the most common technique, involving the application of liquid nitrogen to the growth. The extreme cold destroys the cells, causing the lesion to blister, scab over, and fall off within days or weeks. A potential side effect is temporary or permanent hypopigmentation, which is a lightening of the skin color in the treated area.
Curettage and Electrodessication
Another widely used approach is curettage, often combined with electrodessication. Curettage uses a surgical instrument to scrape the lesion off the skin surface. Electrodessication uses a targeted electric current to burn and destroy the remaining tissue and control bleeding.
Shave Excision
For larger or thicker growths, or when diagnosis confirmation is needed, a shave excision may be performed. This procedure uses a thin blade to carefully shave the growth away, preserving a tissue sample for laboratory analysis.
When to Seek Medical Evaluation
While seborrheic keratoses are non-cancerous, they can sometimes resemble early-stage skin cancers, such as melanoma or basal cell carcinoma. Therefore, any new or changing growth should be evaluated by a medical professional to ensure an accurate diagnosis. A doctor can typically identify an SK by visual examination, sometimes using a dermatoscope, a handheld lighted microscope, for a closer look.
Seek evaluation if a growth exhibits suspicious changes, particularly if it is growing rapidly or has irregular borders and multiple colors. Other concerning signs include persistent irritation, bleeding that does not heal, or the sudden appearance of many growths at once. If a doctor suspects a malignancy, a biopsy will be performed, involving the removal of part or all of the lesion for microscopic examination.