View source for Keratosis Seborrheic

{{Infobox disease
| Name           = Seborrheic keratosis
| Image          = Seborrheic keratosis on human back.jpg
| Caption        = Many seborrheic keratoses on the back of a person with [[Leser–Trélat sign]] due to colon cancer.
| DiseasesDB     = 29386
| ICD10          = {{ICD10|L|82||l|80}} 
| ICD9           = {{ICD9|702.1}} 
| ICDO           = 
| OMIM           = 182000
| MedlinePlus    = 000884
| eMedicineSubj  = derm
| eMedicineTopic = 397
| MeshID         = D017492 
}}
A '''seborrheic keratosis''' (also known as "seborrheic verruca," and "senile wart"<ref name="Fitz2">Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.</ref>{{rp|767}}<ref name="Andrews">{{cite book |author=James, William D.; Berger, Timothy G.; et al. |title=Andrews' Diseases of the Skin: clinical Dermatology |publisher=Saunders Elsevier |location= |year=2006 |pages= |isbn=0-7216-2921-0 |oclc= |doi= |accessdate=}}</ref>{{rp|637}}) is a noncancerous [[Benign tumor|benign skin growth]] that originates in [[keratinocyte]]s. Like [[liver spot]]s, seborrheic keratoses are seen more often as people age.<ref name="cleve">[http://my.clevelandclinic.org/healthy_living/skin_care/hic_moles_freckles_skin_tags_benign_lentigines_and_seborrheic_keratoses.aspx Moles, Freckles, Skin Tags, Benign Lentigines, and Seborrheic Keratoses] from the [[Cleveland Clinic]] website</ref> In fact, they are sometimes humorously referred to as the "[[barnacles]] of old age".<ref>{{cite web|url=http://www.medterms.com/script/main/art.asp?articlekey=11538 |title=Keratosis, seborrheic definition - Medical Dictionary definitions of popular medical terms easily defined on MedTerms |publisher=Medterms.com |date=2012-03-19 |accessdate=2013-02-08}}</ref>

The [[lesion]]s 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 {{convert|2.5|cm|in|sigfig=1}} across.<ref name="mayosymp">[http://www.mayoclinic.com/health/seborrheic-keratosis/DS00846/DSECTION=symptoms Seborrheic keratosis: Symptoms], from the [[Mayo Clinic]] website</ref>  They can resemble [[wart]]s,<ref name="cleve"/> though they have no viral origins. They can also resemble [[melanoma]] [[skin cancer]], though they are unrelated to melanoma.  Because only the top layers of the [[Epidermis (skin)|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]],{{citation needed (lead)|date=July 2014}} and therefore such [[nomenclature]] is discouraged.{{by whom|date=July 2014}}


==Epidemiology==
Presence and frequency increase with age: almost all elderly patients have some. An Australian study found 100% of the over-50-year-olds in their sample had at least one seborrhoeic keratosis (median number of 23 keratoses in the 51-75 year range, and 69 keratoses in the over-75-year-olds).<ref>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. [abstract]</ref>

Onset is usually in middle age, although they are a common finding in younger patients&mdash;found in 12% of 15-year-olds to 25-year-olds&mdash;making the term "senile keratosis" a misnomer.<ref>Gill D, Dorevitch A, Marks R; The prevalence of seborrheic keratoses in people aged 15 to 30 years: is the term senile keratosis redundant? Arch Dermatol. 2000 Jun;136(6):759-62. [abstract]</ref>

No difference in prevalence exists between the sexes. There is less prevalence in people with darker skin.{{citation needed|date=July 2012}}

==Classification==
Seborrheic keratoses may be divided into the following types:<ref name="Fitz2"/>{{rp|769–770}}

* [[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) -- Often are light brown to off-white.  Pinpoint to a few millimeters in size.  Often found on the [[distal tibia]], ankle, and foot.<ref>{{cite web|url=http://emedicine.medscape.com/article/1059798-overview |title=Stucco Keratosis |publisher= Emedicine.medscape.com |author=  Raymond T. Kuwahara, MD|accessdate=2013-02-08}}</ref>
* [[Clonal seborrheic keratosis]]
* [[Irritated seborrheic keratosis]] (basosquamous cell acanthoma, inflamed seborrheic keratosis)
* [[Seborrheic keratosis with squamous atypia]]
* [[Melanoacanthoma]] (pigmented seborrheic keratosis)
* [[Dermatosis papulosa nigra]]—Commonly found among adult African Americans, presents on the face as small benign papules from a pinpoint to a few millimeters in size.<ref>{{cite web|url=http://emedicine.medscape.com/article/1056854-overview |title=Dermatosis Papulosa Nigra |publisher=Emedicine.medscape.com |author= Mehran Nowfar-Rad, MD |accessdate= 2013-02-08}}</ref>
* [[Inverted follicular keratosis]]<ref>Busam Klaus J., ''Dermatopathology'' s.341; 2010 Saunders ISBN 978-0-443-06654-2</ref>

Also see:
* [[Leser-Trélat sign|The sign of Leser-Trélat]]

==Diagnosis==
[[File:Seborrheic keratosis (1).jpg|thumb]]
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.<ref>http://ssai-starss.com/seborrheic-keratosis-scalp-etiology-treatment</ref> If in doubt, a [[skin biopsy]] should be performed.  Thin seborrheic keratoses on facial skin can be very difficult to differentiate from [[lentigo maligna]] even with [[dermatoscopy]].

Clinically, [[nevus|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, condylomas and seborrheic keratoses can be difficult to differentiate, even on biopsy.

==Treatment==
No treatment of seborrheic keratoses is necessary.<ref name="cleve"/>  There is a small risk of localized [[infection]] caused by picking at the lesion.  If a growth becomes excessively itchy or is irritated by clothing or jewelry, it can be removed.

Small lesions can be treated with light [[electrocautery]].  Larger lesions can be treated with [[electrodesiccation and curettage]], [[biopsy|shave excision]], or [[cryosurgery]].  When correctly performed, removal of seborrheic keratoses will not cause much visible scarring except in persons with dark skin tones.

==Cause==
The causes of seborrheic keratosis are unclear.<ref name="cleve"/> Because seborrheic keratoses are common on sun exposed areas such as the back, arms, face, and neck, [[ultraviolet light]] may play a role, as may genetics. However, they are also found on skin that has not been exposed to the sun.<ref name="mayocause">[http://www.mayoclinic.com/health/seborrheic-keratosis/DS00846/DSECTION=causes Seborrheic keratosis: Causes], from the [[Mayo Clinic]] website</ref> A mutation of a gene coding for a [[growth factor receptor]], ([[FGFR3]]), has been associated with seborrheic keratosis.<ref name="pmid17568799">{{cite journal |author=Hafner C, Hartmann A, Vogt T |title=FGFR3 mutations in epidermal nevi and seborrheic keratoses: lessons from urothelium and skin |journal=J. Invest. Dermatol. |volume=127 |issue=7 |pages=1572–3 |year=2007 |pmid=17568799 |doi=10.1038/sj.jid.5700772}}</ref>

==Etymology==
The term "seborrheic keratosis" combines the adjective form of [[wikt:seborrhea|seborrhea]],<ref>[http://medical.merriam-webster.com/medical/seborrheic Seborrheic], from [[Merriam-Webster]]'s online medical dictionary</ref> [[keratinocyte]] (referring to the part of the [[Epidermis (skin)|epidermis]] that produces [[keratin]]), and the suffix [[wikt:-osis|-osis]], meaning abnormal.<ref>[http://www.merriam-webster.com/dictionary/-osis Suffix "-osis"] from the Merriam-Webster website</ref>

==References==
{{reflist|colwidth=30em}}

==External links==
{{Commons category|Seborrheic keratosis}}
* {{DermAtlas|185}}

{{Diseases of the skin and appendages by morphology}}
{{Cutaneous ketatosis, ulcer, atrophy, necrobiosis, and vasculitis}}
{{Skin tumors, epidermis}}

{{DEFAULTSORT:Seborrheic Keratosis}}
[[Category:Epidermal nevi, neoplasms, cysts]]