Skin Health More Skin Conditions An Overview of Seborrheic Keratosis By Heather L. Brannon, MD Heather L. Brannon, MD Heather L. Brannon, MD, is a family practice physician in Mauldin, South Carolina. She has been in practice for over 20 years. Learn about our editorial process Updated on March 07, 2021 Medically reviewed by Casey Gallagher, MD Medically reviewed by Casey Gallagher, MD Casey Gallagher, MD, is board-certified in dermatology and works as a practicing dermatologist and clinical professor. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents Symptoms Causes Diagnosis Treatment Seborrheic keratosis is a dermatologic condition characterized by wart-like growths that may appear anywhere on the skin except for the palms and soles. Growths can vary in appearance but are typically: Light tan to dark brownRound,Waxy or wartyHave a stuck-on-the-skin appearance While they're harmless, some people seek treatment for aesthetic purposes and because the growths can become irritated or get caught on clothes and jewelry. Seborrheic keratoses develop in a type of skin cell called a keratinocyte on the outermost layer of skin (epidermis). While most dermatologists can diagnose them by appearance alone, they may perform a skin biopsy to rule out worrisome conditions like skin cancer. Some call seborrheic keratosis growths "the barnacles of aging," as they're most common after age 50. Symptoms of Seborrheic Keratosis Seborrheic keratosis is a noncancerous skin growth that has the following typical characteristics: Rests flat against the skin or is raisedStarts off as a small, round bump that then thickens and develops a waxy or wart-like appearance (although in some cases, the surface is smooth)Usually brown but may also be white, black, yellow, or greyDevelops anywhere on the skin (e.g., chest, back, face, and neck), but not on the palms and solesAppears on its own or within groupsRanges in size from a pinpoint to over an inch in diameter This photo contains content that some people may find graphic or disturbing. See Photo DermNet / CC BY-NC-ND This photo contains content that some people may find graphic or disturbing. See Photo DermNet / CC BY-NC-ND Because only the top skin layer is involved, seborrheic keratosis often has a "pasted-on" appearance, similar to a barnacle. The number of growths typically increases as you age. Seborrheic keratoses are not painful but may itch, especially as you get older. If scratched or picked at, the growths can become irritated. Presence of Other Symptoms While seborrheic keratosis is considered a benign skin condition, in rare cases, skin cancer (e.g., squamous cell carcinoma or basal cell carcinoma) can arise from cells that are contained within a seborrheic keratosis. Research suggests that people with a suppressed immune system may have an increased risk of this phenomenon, which is called a malignant or cancerous transformation of a seborrheic keratosis. This is why careful observation of these growths by a dermatologist is important, especially if atypical signs are present, such as: Ulceration (sores)Excoriations (scratch marks)RednessBleeding on or around seborrheic keratoses Skin Cancer Causes The precise cause of seborrheic keratosis remains unknown. Experts believe genes play a role, as these growths tend to run in families. Other factors that may increase your chances of developing them include: Sunlight exposure Chronic friction (such as inside skin folds) Exposure to viruses, specifically the human papillomavirus (HPV), although this theory has lost a lot of favor over the years Diagnosis A dermatologist can usually diagnose seborrheic keratosis simply by its outright appearance or by using a lighted instrument called a dermatoscope. However, in some instances, if the growth looks suspicious for skin cancer or there's any doubt about what they are, a skin biopsy can confirm a diagnosis. Seborrheic keratosis can be mistaken for: Common wart Pre-cancerous lesion called actinic keratosis Acanthosis nigricans (a sign of insulin resistance) This photo contains content that some people may find graphic or disturbing. See Photo Viral warts on hand. DermNet / CC BY-NC-ND This photo contains content that some people may find graphic or disturbing. See Photo Actinic keratosis. DermNet / CC BY-NC-ND The different types of skin biopsies that may be performed include: Shave biopsy: The lesion is shaved to remove a tissue sample.Punch biopsy: A hole-punch-type device removes a narrow cylinder of tissue.Excisional biopsy: The entire lesion is removed with a scalpel. A pathologist then examines the skin samples under a microscope. If they find cancer cells, you'll need additional testing to determine the stage of the cancer, which will guide treatment. Treatment Seborrheic keratosis doesn't typically need treatment unless you consider it cosmetically undesirable, it's uncomfortably itchy, or it's easily irritated. The good news is that there are several different treatment options available: Cryotherapy with liquid nitrogen: The growth is frozen off with liquid nitrogen (an extremely cold liquid)Shave excision: It's removed with a sterile razorCurettage: It's scooped out with an instrument called a curetteElectrocautery: The tissue is burned with an electrical currentChemical peel: A solution such as trichloroacetic acid causes the growth to slough offAblative laser treatment: A laser removes the layer of skin Research suggests that laser therapy is a better alternative than cryotherapy, as it's less likely to cause hyperpigmentation (when removal of the growth causes darkening of the skin). A Word From Verywell Seborrheic keratosis can sometimes be difficult to distinguish from skin cancer, especially when it first appears. It's important to not make assumptions about any new spots, patches, or growths that develop on your skin. Be proactive and see a dermatologist for a proper diagnosis and treatment plan. 10 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Cedars-Sinai. Seborrheic Keratosis. American Academy of Dermatology Association. Seborrheic Keratoses: Overview. American Academy of Dermatology Association. Seborrheic Keratoses: Signs and Symptoms. Conic RZ, Napekoski K, Schuetz H, Piliang M, Bergfeld W, Atanaskova Mesinkovska N. The role of immunosuppression in squamous cell carcinomas arising in seborrheic keratosis. J Am Acad Dermatol. 2017 Jun;76(6):1146-1150. doi: 10.1016/j.jaad.2016.12.002 Cimpean I, Theate I, Vanhooteghem O. Seborrheic keratosis evolution into squamous cell carcinoma: A truly modified sun-related tumor? A case report and review of the literature. Dermatol Reports. 2019 Apr 17;11(1):7999. doi: 10.4081/dr.2019.7999 American Academy of Dermatology Association. Seborrheic Keratoses: Who Gets and Causes. Del rosso JQ. A Closer Look at Seborrheic Keratoses: Patient Perspectives, Clinical Relevance, Medical Necessity, and Implications for Management. J Clin Aesthet Dermatol. 2017;10(3):16-25. Rashmi GS Phulari et al. Seborrheic keratosis. J Oral Maxillofac Pathol. 2014;18(2):327-30. DOI: 10.4103/0973-029X.140926 Wollina U. Seborrheic Keratoses - The Most Common Benign Skin Tumor of Humans. Clinical presentation and an update on pathogenesis and treatment options. Open Access Maced J Med Sci. 2018;6(11):2270-2275. doi:10.3889/oamjms.2018.460 Gurel MS, Aral BB. Effectiveness of erbium:YAG laser and cryosurgery in seborrheic keratoses: Randomized, prospective intraindividual comparison study. J Dermatolog Treat. 2015 Oct;26(5):477-80. doi: 10.3109/09546634.2015.1024597 Additional Reading Bedir R, Yurdakul C, Gucer H, Sehitoglu I. Basal Cell Carcinoma Arising within Seborrheic Keratosis. J Clin Diagn Res. 2014; 8(7): YD06-YD07. doi:10.7860/JCDR/2014/8665.4604 Boyd A, Su P, Shyr Y, et al. Squamous cell carcinomas in situ arising in seborrheic keratoses: an association with concomitant immunosuppression? Int J Dermatol. 2014;53(11):1346-50. doi:10.1111/ijd.12086 By Heather L. Brannon, MD Heather L. Brannon, MD, is a family practice physician in Mauldin, South Carolina. She has been in practice for over 20 years. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit