Seborrheic keratosis
Encyclopedia
A seborrheic keratosis is a noncancerous benign skin growth that originates in keratinocyte
s. Like liver spots, seborrheic keratoses are seen more often as people age. In fact they are sometimes humorously referred to as the "barnacles of old age". http://www.medterms.com/script/main/art.asp?articlekey=11538
They appear in various colors, from light tan to black. They are round or oval, feel flat or slightly elevated (like the scab from a healing wound), and range in size from very small to more than 2.5 centimetre (0.984251968503937 in) across. They can resemble wart
s, though they have no viral origins. They can also resemble melanoma
skin cancer
, though they are unrelated to melanoma as well. Because only the top layers of the epidermis are involved, seborrheic keratoses are often described as having a "pasted on" appearance. Some dermatologists refer to seborrheic keratoses as "seborrheic warts"; these lesions, however, are usually not associated with HPV, and therefore such nomenclature
should be discouraged.
Also see:
should be performed. Thin seborrheic keratoses on facial skin can be very difficult to differentiate from lentigo maligna
even with dermatoscopy
.
Clinically, epidermal nevi
are similar to seborrheic keratoses in appearance. Epidermal nevi are usually present at or near birth. Condyloma
s and wart
s can clinically resemble seborrheic keratoses, and dermatoscopy
can be helpful. On the penis and genital skin, differentiation between condylomas and seborrheic keratoses can be difficult and may require a skin biopsy
.
caused by picking at the lesion. If a growth becomes excessively itchy or is irritated by clothing or jewelry, it can be removed by cryosurgery
.
Small lesions can be treated with light electrocautery. Larger lesions can be treated with electrodesiccation and curettage, shave excision
, or cryotherapy
. When correctly performed, removal of seborrheic keratoses will not cause much visible scarring except in persons with dark skin tones.
, (FGFR3
), has been associated with seborrheic keratosis.. Although a direct cause-effect relationship between physiological stress
and tumors in general has not been medically established, stress is medically recognized as a potential factor in the exacerbation of preexisting tumors, including those which are benign. In this view, physiological stress
can worsen a preexisting condition such as seborrheic keratosis
.
Seborheic keratosis can also be one of the many symptoms of gastrointestinal malignancies.
(referring to the part of the epidermis that produces keratin
), and the suffix -osis, meaning abnormal.
Keratinocyte
Keratinocytes are the predominant cell type in the epidermis, the outermost layer of the human skin, constituting 95% of the cells found there. Those keratinocytes found in the basal layer of the skin are sometimes referred to as "basal cells" or "basal keratinocytes"...
s. Like liver spots, seborrheic keratoses are seen more often as people age. In fact they are sometimes humorously referred to as the "barnacles of old age". http://www.medterms.com/script/main/art.asp?articlekey=11538
They appear in various colors, from light tan to black. They are round or oval, feel flat or slightly elevated (like the scab from a healing wound), and range in size from very small to more than 2.5 centimetre (0.984251968503937 in) across. They can resemble wart
Wart
A wart is generally a small, rough growth, typically on a human’s hands or feet but often other locations, that can resemble a cauliflower or a solid blister. They are caused by a viral infection, specifically by human papillomavirus 2 and 7. There are as many as 10 varieties of warts, the most...
s, though they have no viral origins. They can also resemble melanoma
Melanoma
Melanoma is a malignant tumor of melanocytes. Melanocytes are cells that produce the dark pigment, melanin, which is responsible for the color of skin. They predominantly occur in skin, but are also found in other parts of the body, including the bowel and the eye...
skin cancer
Skin cancer
Skin neoplasms are skin growths with differing causes and varying degrees of malignancy. The three most common malignant skin cancers are basal cell cancer, squamous cell cancer, and melanoma, each of which is named after the type of skin cell from which it arises...
, though they are unrelated to melanoma as well. Because only the top layers of the epidermis are involved, seborrheic keratoses are often described as having a "pasted on" appearance. Some dermatologists refer to seborrheic keratoses as "seborrheic warts"; these lesions, however, are usually not associated with HPV, and therefore such nomenclature
Nomenclature
Nomenclature is a term that applies to either a list of names or terms, or to the system of principles, procedures and terms related to naming - which is the assigning of a word or phrase to a particular object or property...
should be discouraged.
Classification
Seborrheic keratoses may be divided into the following types:- Common seborrheic keratosisCommon seborrheic keratosisCommon seborrheic keratosis is a common benign cutaneous condition characterized by a skin lesion with a dull or lackluster surface....
(Basal cell papilloma, Solid seborrheic keratosis) - Reticulated seborrheic keratosisReticulated seborrheic keratosisReticulated seborrheic keratosis is a common benign cutaneous condition characterized by a skin lesion with a dull or lackluster surface, and with keratin cysts seen histologically....
(Adenoid seborrheic keratosis) - Stucco keratosisStucco keratosisStucco keratosis is a common benign cutaneous condition characterized by a skin lesion with a dull or lackluster surface, and with church-spire-like projections of epidermal cells around collagen seen histologically....
(Digitate seborrheic keratosis, Hyperkeratotic seborrheic keratosis, Serrated seborrheic keratosis, Verrucous seborrheic keratosis) - Clonal seborrheic keratosisClonal seborrheic keratosisClonal seborrheic keratosis is a common benign cutaneous condition characterized by a skin lesion with a dull or lackluster surface, and with round, loosely packed nests of cells seen histologically....
- Irritated seborrheic keratosisIrritated seborrheic keratosisIrritated seborrheic keratosis is a common benign cutaneous condition characterized by a skin lesion with a dull or lackluster surface....
(Basosquamous cell acanthoma, Inflamed seborrheic keratosis) - Seborrheic keratosis with squamous atypiaSeborrheic keratosis with squamous atypiaSeborrheic keratosis with squamous atypia is a less common cutaneous condition characterized by a skin lesion with a dull or lackluster surface, and with round, loosely packed nests of cells seen histologically....
- MelanoacanthomaMelanoacanthomaMelanoacanthoma is a common, benign, darkly pigmented cutaneous condition characterized by a skin lesion with a dull or lackluster surface.It involves a proliferation of keratinocytes and melanocytes....
(Pigmented seborrheic keratosis) - Dermatosis papulosa nigraDermatosis papulosa nigraDermatosis papulosa nigra is a condition of many small, benign skin lesions on that face that closely simulate seborrheic keratoses, a condition generally presenting on dark-skinned individuals....
Also see:
- The sign of Leser-TrélatLeser-Trelat signThe Leser-Trélat sign is the explosive onset of multiple seborrheic keratoses , often with an inflammatory base. This can be an ominous sign of internal malignancy as part of a paraneoplastic syndrome...
Dermatosis papulosis nigra
Commonly found among adult blacks, presents on the face as small benign papules from a pinpoint to a few millimeters in size.Stucco keratosis
Often are light brown to off-white. Pinpoint to a few millimeters in size. Often found on the distal tibia, ankle, and foot.Diagnosis
Visual diagnosis is made by the "stuck on" appearance, horny pearls or cysts embedded in the structure. Darkly pigmented lesions can be hard to distinguish from nodular melanomas. If in doubt, a skin biopsySkin biopsy
Skin biopsy is a biopsy technique in which a skin lesion is removed and sent to the pathologist to render a microscopic diagnosis. It is usually done under local anesthetic in a physician's office, and results are often available in 4 to 10 days. It is commonly performed by dermatologists. Skin...
should be performed. Thin seborrheic keratoses on facial skin can be very difficult to differentiate from lentigo maligna
Lentigo maligna
Lentigo maligna is a melanoma in situ that consists of malignant cells but does not show invasive growth. Lentigo maligna is not the same as lentigo maligna melanoma, and should be discussed separately. It typically progresses very slowly and can remain in a non-invasive form for years...
even with dermatoscopy
Dermatoscopy
Dermatoscopy is the examination of skin lesions with a dermatoscope...
.
Clinically, epidermal nevi
Nevus
Nevus is the medical term for sharply-circumscribed and chronic lesions of the skin. These lesions are commonly named birthmarks and moles. Nevi are benign by definition...
are similar to seborrheic keratoses in appearance. Epidermal nevi are usually present at or near birth. Condyloma
Condyloma
Condyloma refers to an infection of the genitals. The two subtypes are:* Condyloma acuminata, or genital warts, caused by human papilloma virus subtypes 6, 11, and others...
s and wart
Wart
A wart is generally a small, rough growth, typically on a human’s hands or feet but often other locations, that can resemble a cauliflower or a solid blister. They are caused by a viral infection, specifically by human papillomavirus 2 and 7. There are as many as 10 varieties of warts, the most...
s can clinically resemble seborrheic keratoses, and dermatoscopy
Dermatoscopy
Dermatoscopy is the examination of skin lesions with a dermatoscope...
can be helpful. On the penis and genital skin, differentiation between condylomas and seborrheic keratoses can be difficult and may require a skin biopsy
Skin biopsy
Skin biopsy is a biopsy technique in which a skin lesion is removed and sent to the pathologist to render a microscopic diagnosis. It is usually done under local anesthetic in a physician's office, and results are often available in 4 to 10 days. It is commonly performed by dermatologists. Skin...
.
Treatment
When correctly diagnosed, no treatment is necessary. There is a small risk of localized infectionInfection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
caused by picking at the lesion. If a growth becomes excessively itchy or is irritated by clothing or jewelry, it can be removed by cryosurgery
Cryosurgery
Cryosurgery is the application of extreme cold to destroy abnormal or diseased tissue. The term comes from the Greek words cryo and surgery meaning "hand work" or "handiwork"....
.
Small lesions can be treated with light electrocautery. Larger lesions can be treated with electrodesiccation and curettage, shave excision
Biopsy
A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...
, or cryotherapy
Cryotherapy
Cryotherapy is the local or general use of low temperatures in medical therapy or the removal of heat from a body part. The term "cryotherapy" comes from the Greek cryo meaning cold and the word therapy meaning cure...
. When correctly performed, removal of seborrheic keratoses will not cause much visible scarring except in persons with dark skin tones.
Cause
The cause of seborrheic keratosis is unclear. Because they are common on sun-exposed areas such as the back, arms, face, and neck, ultraviolet light may play a role, as may genetics. A mutation of a gene coding for a growth factor receptorGrowth factor receptor
A growth factor receptor is a receptor which binds to growth factor.These receptors may use the JAK/STAT, MAP kinase, and PI3 kinase pathways....
, (FGFR3
FGFR3
Fibroblast growth factor receptor 3 is a protein that in humans is encoded by the FGFR3 gene. FGFR3 has also been designated as CD333 .-Structure and function:-Disease linkage:...
), has been associated with seborrheic keratosis.. Although a direct cause-effect relationship between physiological stress
Stress (biology)
Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
and tumors in general has not been medically established, stress is medically recognized as a potential factor in the exacerbation of preexisting tumors, including those which are benign. In this view, physiological stress
Stress (biology)
Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
can worsen a preexisting condition such as seborrheic keratosis
Seborrheic keratosis
A seborrheic keratosis is a noncancerous benign skin growth that originates in keratinocytes. Like liver spots, seborrheic keratoses are seen more often as people age. In fact they are sometimes humorously referred to as the "barnacles of old age". They appear in various colors, from light tan to...
.
Seborheic keratosis can also be one of the many symptoms of gastrointestinal malignancies.
Etymology
The term "seborrheic keratosis" combines the adjective form of seborrhea, keratinocyteKeratinocyte
Keratinocytes are the predominant cell type in the epidermis, the outermost layer of the human skin, constituting 95% of the cells found there. Those keratinocytes found in the basal layer of the skin are sometimes referred to as "basal cells" or "basal keratinocytes"...
(referring to the part of the epidermis that produces keratin
Keratin
Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...
), and the suffix -osis, meaning abnormal.