> Table of Contents > Keratosis, Seborrheic
Keratosis, Seborrheic
Jelaun Newsome, DO
image BASICS
  • One of the most common benign tumors of the epidermis
  • Formed from keratinocytes
  • Frequently appears in multiples on the head, neck, and trunk of older individuals but may occur on any hair-bearing area of the body. Lesions spare the palms and soles.
  • Typically are light brown to black, sharply demarcated, round, or elongated lesions with a velvety, verrucous-like, “stuck-on” appearance; lesions may also appear waxy yellow or pink.
  • Clinical variants include the following:
    • Common seborrheic keratosis
    • Dermatosis papulosa nigra
    • Stucco keratosis
    • Flat seborrheic keratosis
    • Pedunculated seborrheic keratosis
  • System(s) affected: integumentary
  • Synonym(s): verruca seborrhoica; seborrheic wart; senile wart; basal cell papilloma; verruca senilis; basal cell acanthoma; benign acanthokeratoma
  • Predominant age
    • Usually appear after the 3rd decade
    • Most commonly seen during middle and older age
    • Can occasionally arise as early as adolescence
  • Predominant sex: male = female
  • Most common among Caucasians, except for the dermatosis papulosa nigra variant, which usually presents in darker skinned individuals
  • 69-100% in patients >50 years of age
  • The prevalence rate increases with advancing age.
  • Seborrheic keratoses are monoclonal tumors.
  • Etiology still is largely unclear.
  • Ultraviolet (UV) light and genetics are thought to be involved.
  • The role of human papillomavirus is uncertain.
An autosomal dominant inheritance pattern is suggested.
  • Advanced age
  • Exposure to UV light and genetic predisposition are possible factors (1).
Sun protection methods may help prevent seborrheic keratoses from developing.
  • Sign of Leser-Trélat: A paraneoplastic syndrome characterized by a sudden eruption of multiple seborrheic keratoses in association with an internal malignancy, most commonly stomach or colon adenocarcinoma. Usually represents a poor prognosis. The validity of this syndrome as a marker for internal malignancy is controversial (2)[B].
  • Documentation of other cutaneous lesions, such as basal cell carcinoma, malignant melanoma, Bowen disease, or squamous cell carcinoma, growing adjacent to or within a seborrheic keratosis, has been reported. The exact relationship between lesions is unclear.
  • Typically begin as oval- or round-shaped, flat, dull, sharply demarcated patches
  • As they mature, may develop into thicker, elevated, uneven, verrucous-like papules, plaques, or peduncles with a waxy or velvety surface, and appear “stuck on” to the skin (3)
  • Commonly appear on sun-exposed areas of the body, predominately the head, neck, or trunk but may appear on any hair-bearing skin
  • Vary in color from black, brown, tan, gray to white, or skin-colored, and range in size, from 1 mm to 4 cm
  • Usually occur as multiples, with patients having >100 is not uncommon.
  • May grow along folds on truncal skin, forming a “Christmas tree” pattern
  • If irritated, may be bleeding, inflamed, painful, pruritic, or crusted
  • Common clinical variants include the following (4):
    • Common seborrheic keratoses: on hair-bearing skin, usually on the face, neck, and trunk; verrucous-like, waxy, or velvety lesions that appear “stuck on” to the skin
    • Dermatosis papulosa nigra: Small black papules that usually appear on the face, neck, chest, and upper back; most common in darker skinned individuals, more common in females; most have a positive family history.
    • Stucco keratoses: small gray-white, rough, verrucous papules; usually occur in large numbers on the lower extremities or forearms; more common in men
    • Flat seborrheic keratoses: oval-shaped, brown patches or macules on face, chest, and upper extremities; increases with age
    • Pedunculated seborrheic keratoses: Hyperpigmented peduncles appear on areas of friction (neck, axilla).
Consider the following diagnoses if the seborrheic keratosis is:
  • Pigmented
    • Malignant melanoma
    • Melanocytic nevus
    • Angiokeratoma
    • Pigmented basal cell carcinoma
  • Lightly pigmented
    • Basal cell carcinoma
    • Bowen disease
    • Condyloma acuminatum
    • Fibroma
    • Verruca vulgaris
    • Eccrine poroma
    • Invasive squamous cell carcinoma
    • Acrochordon
    • Acrokeratosis verruciformis of Hopf
    • Follicular infundibulum tumor
  • Flat
    • Solar lentigo
    • Verrucae planae juveniles
  • Hyperkeratotic
    • Actinic keratosis
Initial Tests (lab, imaging)
Not needed unless internal malignancy is suspected
Diagnostic Procedures/Other
  • The diagnosis can usually be made based on clinical appearance.
  • Dermoscopy
    • Can aid in diagnosis
    • Common findings are comedo-like openings, fissures, ridges, sharply demarcated borders, milia-like cysts, pseudofollicular openings, hairpin vessels, and horn pseudocysts (5,6).
  • Biopsy and histologic exam should be performed if the seborrheic keratosis
    • Is atypical
    • Has inflammation
    • Recently changed in appearance
    • Diagnosis remains unclear.
Test Interpretation
  • Histologic findings include the following:
    • Acanthosis and papillomatosis due to basaloid cell proliferation
    • “Squamous eddies” or squamous epithelial cell clusters
    • Hyperpigmentation
    • Hyperkeratosis
    • Horn cysts
    • Pseudocysts
  • Several histologic variants exist.

  • Treatment is not usually necessary due to the benign nature of the lesions.
  • Removal of seborrheic keratoses may be indicated if
    • Symptomatic
    • Aesthetically displeasing or undesirable (common)
    • There is a question of malignancy.
Current topical treatments of seborrheic keratoses are less effective than a surgical approach.
  • New seborrheic keratoses appear abruptly.
  • A seborrheic keratosis becomes inflamed or changes in appearance.
  • A surgical approach to treatment is preferred.
  • Choice depends on physician preference and availability of the treatment.
  • The following procedures are used:
    • Cryotherapy (liquid nitrogen)
      • Spray flat lesions for 5 to 10 seconds; may require more time or additional treatments if the seborrheic keratosis is thicker
      • Possible complications include scarring, hypopigmentation, recurrence.
    • Curettage
    • Electrodessication
    • Shave excision
    • Excisional biopsy
    • Chemical peel
  • Use of following laser treatments have been reported:
    • Ablative CO2
    • Ablative erbium-YAG
    • Argon
    • 492 nm
    • 510 nm
    • Alexandrite lasers
  • No statistically significant differences were found in patient's ratings of cosmetic appearance between cryotherapy and curettage. The majority of patients preferred cryotherapy over curettage due to decreased postoperative wound care, despite the increased discomfort experienced and increased frequency of seborrheic keratosis remaining after cryotherapy when compared to curettage (7)[B].
Patient Monitoring
After initial diagnosis, follow-up is not usually required unless
  • Inflammation or irritation develops.
  • There is a change in appearance.
  • New seborrheic keratoses suddenly appear.
  • Sun-protective methods may help reduce seborrheic keratosis development.
  • Patient education materials
    • http://www.aad.org/dermatology-a-to-z/diseases-and-treatments/q-t/seborrheic-keratoses
    • www.cdc.gov/cancer/skin/basic_info/prevention.htm
  • Seborrheic keratoses generally do not become malignant.
  • Sign of Leser-Trélat usually represents a poor prognosis.
1. Saeed AK, Salmo N. Epidermal growth factor receptor expression in mice skin upon ultraviolet B exposure — seborrheic keratosis as a coincidental and unique finding. Adv Biomed Res. 2012;1:59.
2. Ponti G, Luppi G, Losi L, et al. Leser-Trélat syndrome in patients affected by six multiple metachronous primitive cancers. J Hematol Oncol. 2010;3:2.
3. Luba MC, Bangs SA, Mohler AM, et al. Common benign skin tumors. Am Fam Physician. 2003;67(4):729-738.
4. Noiles K, Vender R. Are all seborrheic keratoses benign? Review of the typical lesion and its variants. J Cutan Med Surg. 2008;12(5):203-210.
5. Marghoob AA, Usatine RP, Jaimes N. Dermoscopy for the family physician. Am Fam Physician. 2013;88(7):441-450.
6. Takenouchi T. Key points in dermoscopic diagnosis of basal cell carcinoma and seborrheic keratosis in Japanese. J Dermatol. 2011;38(1):59-65.
7. Wood LD, Stucki JK, Hollenbeak CS, et al. Effectiveness of cryosurgery vs curettage in the treatment of seborrheic keratoses. JAMA Dermatol. 2013;149(1):108-109.
Additional Reading
  • Culbertson GR. 532-nm diode laser treatment of seborrheic keratoses with color enhancement. Dermatol Surg. 2008;34(4):525-528.
  • Draelos ZD, Rizer RL, Trookman NS. A comparison of postprocedural wound care treatments: do antibiotic-based ointments improve outcomes? J Am Acad Dermatol. 2011;64(Suppl 3):S23-S29.
  • Garcia MS, Azari R, Eisen DB. Treatment of dermatosis papulosa nigra in 10 patients: a comparison trial of electrodesiccation, pulsed dye laser, and curettage. Dermatol Surg. 2010;36(12):1968-1972.
  • Georgieva IA, Mauerer A, Groesser L, et al. Low incidence of oncogenic EGFR, HRAS, and KRAS mutations in seborrheic keratosis. Am J Dermatopathol. 2014;36(8):635-642.
  • Hafner C, Vogt T. Seborrheic keratosis. J Dtsch Dermatol Ges. 2008;6(8):664-677.
  • 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.
  • Krupashankar DS. Standard guidelines of care: CO2 laser for removal of benign skin lesions and resurfacing. Indian J Dermatol Venereol Leprol. 2008;74(Suppl):S61-S67.
  • Rajesh G, Thappa DM, Jaisankar TJ, et al. Spectrum of seborrheic keratoses in South Indians: a clinical and dermoscopic study. Indian J Dermatol Venereol Leprol. 2011;77(4):483-488.
  • Taylor SC, Averyhart AN, Heath CR. Postprocedural wound-healing efficacy following removal of dermatosis papulosa nigra lesions in an African American population: a comparison of a skin protectant ointment and a topical antibiotic. J Am Acad Dermatol. 2011;64(3 Suppl):S30-S35.
  • L82.1 Other seborrheic keratosis
  • L82.0 Inflamed seborrheic keratosis
Clinical Pearls
  • Seborrheic keratoses are one of the most common benign tumors of the epidermis.
  • Prevalence increases with age.
  • Underlying internal malignancy should be considered if large numbers of seborrheic keratoses appear suddenly.