Seborrheic Keratosis - Western SummaryWestern Medicine Summary

Western Medicine

Western Summary

Seborrheic keratoses are rough lesions that grow on the body. They are skin growths that typically start to appear when people turn 40 years old.[1] A clinical study shows that 100% of people above the age of 50 have had at least one seborrheic keratosis.[2] Although they are typically seen in middle-aged adults, seborrheic keratosis lesions can also be found in 12% of people between the ages 15 and 25.[2] They are more common in Caucasians, and equally common in men and women.[3] They can grow anywhere there is skin, especially on the back. 


Seborrheic keratoses appear as round or oval rough spots that range from very small to up to several inches in size. They grow from the upper layers of the skin surface, called the epidermis, and are often described as having a “stuck-on” appearance. They can have various colors, from flesh colored and light tan, to dark brown and gray. Sometimes seborrheic keratoses develop next to other skin growths to form a “collision tumor.”[4] These neighboring growths range from benign growths such as moles and sun spots to skin cancers. So it is important to have any abnormal looking lesion evaluated by a medical professional. 


The cause of seborrheic keratosis is not well understood. Several factors are associated with their formation: 

  • Aging: The formation of seborrheic keratosis is closely linked to age.[5] The older you are, the more you will have. 
  • Sunlight: Seborrheic keratosis occur more commonly and starts at an earlier age in people living in tropical climates. They are also more common in areas that get more sun exposure, such as the head and neck.[2] 
  • Trauma: Seborrheic keratosis are usually harmless unless they are irritated when rubbed or scratched by jewelry, shaving, or clothing. Irritated seborrheic keratosis can cause itching, pain, bleeding and can occasionally become infected.
  • Cancer: A rare finding discovered that rapid onset of multiple seborrheic keratoses together with enlargement of preexisting seborrheic keratosis lesions can be a clue of internal cancer, called the Leser-Trelat Sign.[6] The most commonly associated cancers are gastrointestinal (liver, stomach, intestines, and pancreas).[7] Other cancers are nasopharynx (the uppermost part of the throat),[8] lung,[9] urinary tract,[10] lymphomas and leukemia.[11-13]


Since seborrheic keratosis are benign, they typically do not require treatment unless they are irritated or when cosmetics is a concern. There is no effective topical treatment for complete clearing of seborrheic keratosis. There are several treatments that can be useful and should be discussed with a medical provider:[14]

  • Topical chemicals: Topical ammonium lactate[15] and alpha hydroxyl acids[16] can decrease the height of seborrheic keratosis. They will not make the seborrheic keratosis go away completely. 
  • Topical retinoids: This treatment can make seborrheic keratosis less noticeable,[17] but they will not make them go away. 
  • Cryotherapy: This treatment involves freezing the seborrheic keratosis with liquid nitrogen.[18] 
  • Electrocautery: This treatment involves carefully destroying the seborrheic keratosis using a metal tip heated by electric current. Sometimes the lesion is scraped off with a round and sharp surgical instrument known as a curette. 
  • Surgical removal: This treatment involves removing the seborrheic keratosis using a razor-like blade or surgical knife by “shaving” the seborrheic keratosis at its base. Stitches are not typically required. Many times the removed sample will be processed and analyzed under a microscope as a biopsy to verify the diagnosis. 
  • Lasers: Various lasers can be used to flatten or lighten the color of seborrheic keratosis.[18,19] 

If any rough lesion is new, abnormal or changing in size, you should consult a doctor for an evaluation.

1.    Kyriakis KP, Alexoudi I, Askoxylaki K, et al. Epidemiologic aspects of seborrheic keratoses. Int J Dermatol.2012;51(2):233-234; PMID: 22250637.

2.    Yeatman JM, Kilkenny M, Marks R. The prevalence of seborrhoeic keratoses in an Australian population: does exposure to sunlight play a part in their frequency? Br J Dermatol.1997;137(3):411-414; PMID: 9349339.

3.    Verhagen AR, Koten JW, Chaddah VK, et al. Skin diseases in Kenya. A clinical and histopathological study of 3,168 patients. Arch Dermatol.1968;98(6):577-586; PMID: 4235165.

4.    Vun Y, De'Ambrosis B, Spelman L, et al. Seborrhoeic keratosis and malignancy: collision tumour or malignant transformation? Australas J Dermatol.2006;47(2):106-108; PMID: 16637805.

5.    Kwon OS, Hwang EJ, Bae JH, et al. Seborrheic keratosis in the Korean males: causative role of sunlight. Photodermatol Photoimmunol Photomed.2003;19(2):73-80; PMID: 12945806.

6.    Husain Z, Ho JK, Hantash BM. Sign and pseudo-sign of Leser-Trelat: case reports and a review of the literature. J Drugs Dermatol.2013;12(5):e79-87; PMID: 23652964.

7.    Gregory B, Ho VC. Cutaneous manifestations of gastrointestinal disorders. Part I. J Am Acad Dermatol.1992;26(2 Pt 1):153-166; PMID: 1552046.

8.    Li M, Yang LJ, Zhu XH, et al. The Leser-Trelat sign is associated with nasopharyngeal carcinoma: case report and review of cases reported in China. Clin Exp Dermatol.2009;34(1):52-54; PMID: 19076792.

9.    Heaphy MR, Jr., Millns JL, Schroeter AL. The sign of Leser-Trelat in a case of adenocarcinoma of the lung. J Am Acad Dermatol.2000;43(2 Pt 2):386-390; PMID: 10901731.

10.    Yaniv R, Servadio Y, Feinstein A, et al. The sign of Leser-Trelat associated with transitional cell carcinoma of the urinary-bladder--a case report and short review. Clin Exp Dermatol.1994;19(2):142-145; PMID: 8050144.

11.    McCrary ML, Davis LS. Sign of Leser-Trelat and mycosis fungoides. J Am Acad Dermatol.1998;38(4):644; PMID: 9555814.

12.    Ikari Y, Ohkura M, Morita M, et al. Leser-Trelat sign associated with Sezary syndrome. J Dermatol.1995;22(1):62-67; PMID: 7897028.

13.    Halevy S, Sandbank M. Transformation of lymphocytoma cutis into a malignant lymphoma in association with the sign of Leser-Trelat. Acta Derm Venereol.1987;67(2):172-175; PMID: 2438886.

14.    Jackson JM, Alexis A, Berman B, et al. Current Understanding of Seborrheic Keratosis: Prevalence, Etiology, Clinical Presentation, Diagnosis, and Management. J Drugs Dermatol.2015;14(10):1119-1125; PMID: 26461823.

15.    Klaus MV, Wehr RF, Rogers RS, 3rd, et al. Evaluation of ammonium lactate in the treatment of seborrheic keratoses. J Am Acad Dermatol.1990;22(2 Pt 1):199-203; PMID: 2138172.

16.    Van Scott EJ, Yu RJ. Alpha hydroxy acids: procedures for use in clinical practice. Cutis.1989;43(3):222-228; PMID: 2523288.

17.    Herron MD, Bowen AR, Krueger GG. Seborrheic keratoses: a study comparing the standard cryosurgery with topical calcipotriene, topical tazarotene, and topical imiquimod. Int J Dermatol.2004;43(4):300-302; PMID: 15090020.

18.    Krupashankar DS, Force IDT. Standard guidelines of care: CO2 laser for removal of benign skin lesions and resurfacing. Indian J Dermatol Venereol Leprol.2008;74 Suppl:S61-67; PMID: 18688106.

19.    Kim YK, Kim DY, Lee SJ, et al. Therapeutic efficacy of long-pulsed 755-nm alexandrite laser for seborrheic keratoses. J Eur Acad Dermatol Venereol.2014;28(8):1007-1011; PMID: 23909912.