Edit concept Question Editor Create issue ticket

Seborrheic Keratosis

A seborrheic keratosis (seborrheic verruca) is a benign, pigmented, superficial epithelial tumor of older adults.


Seborrheic keratoses are often asymptomatic but they may be a source of constant worry for the patient. The lesions may rub on clothing and become itchy. Following the patient’s indulgement to itching, the lesions can easily become inflamed, begin bleeding or get infected in rare cases [8].

The lesions often have a waxy or wart-like growth typically seen on the face, chest, shoulder or back of the patient. The common characteristics of seborrheic keratosis lesions include:

  • Light tan or brown black lesions
  • Round or oval shaped in size
  • Characteristic “pasted on” appearance
  • Flat or slightly elevated with a scaly surface
  • Ranges in size from very small to 1 inch
  • Can be itchy
  • Growths may be single or clustered in patches
Koebner Phenomenon
  • Based on our results, we suggest a diagnostic algorithm using Koebner's phenomenon, dermoscopic findings, distribution of each lesion and biopsy for multiple VP-like lesions in adults, and we think it will be a very useful diagnostic tool in daily clinical[ncbi.nlm.nih.gov]
Follicular Plugging
  • Clinical diagnostic criteria for early lesions included discrete, round, or oval skin-colored papules with distinct keratotic and follicular plugging, stuck-on appearance, and colors ranging from skin-colored to heavily pigmented.[doi.org]


Diagnosis is often clinical following inspection of the growth. In cases where the diagnosis is difficult and a cancer is suspected, a biopsy may be needed [9]. There is no need for laboratory tests in many cases.

Malassezia Furfur
  • Malassezia sympodialis, Malassezia furfur, and the non-lipid dependent Malassezia pachydermatis.[web.archive.org]


The height of seborrheic keratosis can be reduced following administration of ammonium lactate and alpha hydroxyl acids [10]. Application of pure trichloroacetic acid can be used in treatment of superficial lesions.

Topical treatment with tazarotene cream 0.1% applied twice each day for 16 weeks may bring about clinical improvement in seborrheic keratosis in 7 out of 15 patients. Other forms of treatment include:

  • Cryosurgery (Freezing with liquid nitrogen)
  • Curettage (Scrapping of the skin’s surface with the aid of a special treatment)
  • Electrocautery (Burning with electric current)
  • Ablation (Vaporising of growth with laser)


Seborrheic keratosis is benign and rarely presents a danger to the health of an individual. The lesions often do not resolve and they grow larger and thicker over a period of time [7].


The causes of seborrheic keratosis have remained unclear but ultraviolet light is suspected to play a role in the formation of the condition due to the fact that seborrheic keratosis is common in sun exposed areas like the back, arms, face and neck [3]. However the lesions have been found in areas often covered from the sun.

Genetics may play a role because it is seen in individuals with the family history. A mutation of a gene coding for a growth factor receptor (FGFR3) has been associated with this condition.


Seborrheic keratosis is one of the most common types of skin tumors as between 60 and 80% of people aged 50 and show seborrheic keratosis [4]. It is rarely seen in people below 30 years of age and both men and women are equally affected.

This benign skin disorder is seen more in people with white skin when compared to people with dark skin. However, black people develop the dermatosis papulosa nigra variant of keratosis. This variant of lesions affects the face, the upper cheeks and lateral orbital areas. They are often heavily pigmented, having very little keratotic element. The onset of this variant is often earlier than what is obtainable with traditional seborrheic keratosis.

Sex distribution
Age distribution


Seborrheic keratosis shows a histologic evidence of proliferation. Following bromodeoxyuridine incorporation studies and immunohistochemistry for proliferation-associated antigens increased cell replication has been noted in seborrheic keratosis [5]. A moderate increase is seen in the rates of apoptosis in all varieties of seborrheic keratosis in comparison to what is obtainable with normal skin.

Reticulated seborrheic keratosis is usually seen on sun-exposed skin. The reticulated type of seborrheic keratosis is believed to develop from solar lentigines.

Epidermal growth factors as well as their receptors have been observed in the progression of seborrheic keratosis and no difference was noted in the expression of immunoreactive growth hormone receptors in keratinocytes from normal epidermis and keratinocytes arising from seborrheic keratosis [6]. BCL2, an apoptosis-suppressing oncogene is low in seborrheic keratosis unlike what is obtainable in squamous cell and basal cell carcinoma where high values of expression are observed. In comparison to normal skin also, no increase is observed in the sonic hedgehog signal transducers patched (ptc) and smoothened (smo) messenger RNA (mRNA) in seborrheic keratosis. Seborrheic keratoses also have varying degrees of pigmentation.


There is no clear prevention path for this condition.


Seborrheic keratosis is a benign and non-cancerous skin condition which often originates in the keratinocytes [1]. It is also known as seborrheic verruca, senile wart and seborrheic warts in some quarters. This condition is seen mostly in older individuals.

The lesions arising from seborrheic keratosis vary in colour ranging from light tan to black. The shape of the lesions is either oval or round and may be flat or slightly elevated. The size of the lesions also varies from small to as much as 2.5 centimetres across the skin surface. Although they bear close resemblance to warts, they do not have any viral connections. They are also unrelated to melanoma but resemble melanoma skin cancer.
Seborrheic keratosis is often described as having a “pasted on” appearance due to the fact that the condition only affects the top layers of the epidermis.

Seborrheic keratoses may be divided into the following types [2]:

  • Common seborrheic keratosis (basal cell papilloma, solid seborrheic keratosis)
  • Reticulated seborrheic keratosis (adenoid seborrheic keratosis)
  • Stucco keratosis (digitate seborrheic keratosis, hyperkeratotic seborrheic keratosis, serrated seborrheic keratosis, verrucous seborrheic keratosis)
  • Clonal seborrheic keratosis
  • Irritated seborrheic keratosis (basosquamous cell acanthoma, inflamed seborrheic keratosis)
  • Seborrheic keratosis with squamous atypia
  • Melanoacanthoma (pigmented seborrheic keratosis)
  • Dermatosis papulosa nigra
  • Inverted follicular keratosis

Patient Information

Seborrheic keratosis refers to one of the most common skin growths not as a result of cancer, seen in older individuals.
A seborrheic keratosis often appears as growths on the face, chest, shoulders or back and the growth is often brown, black or light tan in colour.

The growth is most of the time waxy, scaly and slightly elevated in appearance. It may appear single in places but most of the time multiple growths are seen in one place. Although these look like skin cancer or warts, they are not cancerous or infectious.
The growth is usually painless, requiring no treatment. However, people who are not comfortable with it often seek treatment. Treatment may be via the use of creams/substances to be rubbed on surfaces or surgery.



  1. Ginarte M, Garcia-Caballero T, Fernandez-Redondo V, Beiras A, Toribio J. Expression of growth hormone receptor in benign and malignant cutaneous proliferative entities. J Cutan Pathol. Jul 2000;27(6):276-82.
  2. Groves RW, Allen MH, MacDonald DM. Abnormal expression of epidermal growth factor receptor in cutaneous epithelial tumours. J Cutan Pathol. Feb 1992;19(1):66-72.
  3. Nanney LB, Ellis DL, Levine J, King LE. Epidermal growth factor receptors in idiopathic and virally induced skin diseases. Am J Pathol. Apr 1992;140(4):915-25.
  4. Nakagawa K, Yamamura K, Maeda S, Ichihashi M. bcl-2 expression in epidermal keratinocytic diseases. Cancer. Sep 15 1994;74(6):1720-4.
  5. Tojo M, Mori T, Kiyosawa H, Honma Y, Tanno Y, Kanazawa KY, et al. Expression of sonic hedgehog signal transducers, patched and smoothened, in human basal cell carcinoma. Pathol Int. Aug 1999;49(8):687-94. 
  6. 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 Sep;137(3):411-4
  7. Busam Klaus J., Dermatopathology s.341; 2010 Saunders ISBN 978-0-443-06654-2
  8. Hafner C, Hartmann A, Vogt T (2007). "FGFR3 mutations in epidermal nevi and seborrheic keratoses: lessons from urothelium and skin". J. Invest. Dermatol. 127 (7): 1572–3.
  9. Tindall JP, Smith JG Jr. Skin lesions of the aged and their association with internal changes. JAMA. Dec 21 1963;186:1039-42.
  10. Memon AA, Tomenson JA, Bothwell J, Friedmann PS. Prevalence of solar damage and actinic keratosis in a Merseyside population. Br J Dermatol. Jun 2000;142(6):1154-9.

Ask Question

5000 Characters left Format the text using: # Heading, **bold**, _italic_. HTML code is not allowed.
By publishing this question you agree to the TOS and Privacy policy.
• Use a precise title for your question.
• Ask a specific question and provide age, sex, symptoms, type and duration of treatment.
• Respect your own and other people's privacy, never post full names or contact information.
• Inappropriate questions will be deleted.
• In urgent cases contact a physician, visit a hospital or call an emergency service!
Last updated: 2019-06-28 11:10