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'''[[Actinic]] keratosis''' (also called "solar keratosis"<ref name="Bolognia" /> and "senile keratosis"<ref name="Bolognia">{{cite book |author=Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. |title=Dermatology: 2-Volume Set |publisher=Mosby |location=St. Louis |year=2007 |pages=Chapter 108 |isbn=1-4160-2999-0 |oclc= |doi= |accessdate=}}</ref>) is a [[premalignant condition]]<ref name="pmid18474700">{{cite journal |author=Prajapati V, Barankin B |title=Dermacase. Actinic keratosis |journal=Can Fam Physician |volume=54 |issue=5 |pages=691, 699 |year=2008 |month=May |pmid=18474700 |pmc=2377206 |doi= |url=http://www.cfp.ca/cgi/pmidlookup?view=long&pmid=18474700}}</ref> of thick, scaly, or crusty patches of skin.<ref name="Fitz2">Freedberg, et. al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.</ref>{{rp|719}}<ref name="pmid16935787">{{cite journal |author=Quaedvlieg PJ, Tirsi E, Thissen MR, Krekels GA |title=Actinic keratosis: how to differentiate the good from the bad ones? |journal=Eur J Dermatol |volume=16 |issue=4 |pages=335–9 |year=2006 |pmid=16935787 |doi= |url=http://www.john-libbey-eurotext.fr/medline.md?issn=1167-1122&vol=16&iss=4&page=335}}</ref> It is more common in fair-skinned people. It is associated with those who are frequently exposed to the sun,<ref>{{DorlandsDict|nine/000954019|actinic keratosis}}</ref> as it is usually accompanied by [[Sun|solar]] damage. Since some of these pre-cancers progress to [[squamous cell carcinoma]],<ref name="pmid16935787"/> they should be treated. Untreated lesions have up to twenty percent risk of progression to squamous cell carcinoma<ref name=weedon>{{cite book |title= Weedon's Skin Pathology, 3rd Edition |last=Weedon |first=David |authorlink=David Weedon |year=2010 |publisher=Elsevier |isbn=978-0-7020-3485-5}}</ref>. [[I do not know where the figure of 20% was gotten from. Most textbooks of dermatology state that around 10% of AKs progress to skin cancer (squamous cell carcinoma, SCC) if left untreated. This "10%" number was derived from no study and crept into the medical literature without factual basis. The only prospective study addressing the malignant transformation of AKs was performed in Australia in the 1980s by Professor Robin Marks, a research dermatologist, and his associates. They found that .24% of actinic keratoses progress to SCC. The 20% figure stated above is 83 times higher than that which Marks found! In reality, as Marks states in his article, '''"the rationale of treating all solar keratoses appears questionable'''." Reference: Marks R, et. al. Spontaneous remission of solar keratoses: the case for conservative
'''[[Actinic]] keratosis''' (also called "solar keratosis"<ref name="Bolognia" /> and "senile keratosis"<ref name="Bolognia">{{cite book |author=Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. |title=Dermatology: 2-Volume Set |publisher=Mosby |location=St. Louis |year=2007 |pages=Chapter 108 |isbn=1-4160-2999-0 |oclc= |doi= |accessdate=}}</ref>) is a [[premalignant condition]]<ref name="pmid18474700">{{cite journal |author=Prajapati V, Barankin B |title=Dermacase. Actinic keratosis |journal=Can Fam Physician |volume=54 |issue=5 |pages=691, 699 |year=2008 |month=May |pmid=18474700 |pmc=2377206 |doi= |url=http://www.cfp.ca/cgi/pmidlookup?view=long&pmid=18474700}}</ref> of thick, scaly, or crusty patches of skin.<ref name="Fitz2">Freedberg, et. al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.</ref>{{rp|719}}<ref name="pmid16935787">{{cite journal |author=Quaedvlieg PJ, Tirsi E, Thissen MR, Krekels GA |title=Actinic keratosis: how to differentiate the good from the bad ones? |journal=Eur J Dermatol |volume=16 |issue=4 |pages=335–9 |year=2006 |pmid=16935787 |doi= |url=http://www.john-libbey-eurotext.fr/medline.md?issn=1167-1122&vol=16&iss=4&page=335}}</ref> It is more common in fair-skinned people. It is associated with those who are frequently exposed to the sun,<ref>{{DorlandsDict|nine/000954019|actinic keratosis}}</ref> as it is usually accompanied by [[Sun|solar]] damage. Since some of these pre-cancers progress to [[squamous cell carcinoma]],<ref name="pmid16935787"/> they should be treated. Untreated lesions have up to twenty percent risk of progression to squamous cell carcinoma<ref name=weedon>{{cite book |title= Weedon's Skin Pathology, 3rd Edition |last=Weedon |first=David |authorlink=David Weedon |year=2010 |publisher=Elsevier |isbn=978-0-7020-3485-5}}</ref>.
management. Br J Dermatol 1986 Dec;115(6):649-655]


When skin is exposed to the sun constantly, thick, scaly, or crusty bumps appear. The scaly or crusty part of the bump is dry and rough. The growths start out as flat scaly areas, and later grow into a tough, wart-like area.
When skin is exposed to the sun constantly, thick, scaly, or crusty bumps appear. The scaly or crusty part of the bump is dry and rough. The growths start out as flat scaly areas, and later grow into a tough, wart-like area.

Revision as of 17:17, 16 October 2011

Actinic keratosis
SpecialtyDermatology Edit this on Wikidata

Actinic keratosis (also called "solar keratosis"[1] and "senile keratosis"[1]) is a premalignant condition[2] of thick, scaly, or crusty patches of skin.[3]: 719 [4] It is more common in fair-skinned people. It is associated with those who are frequently exposed to the sun,[5] as it is usually accompanied by solar damage. Since some of these pre-cancers progress to squamous cell carcinoma,[4] they should be treated. Untreated lesions have up to twenty percent risk of progression to squamous cell carcinoma[6].

When skin is exposed to the sun constantly, thick, scaly, or crusty bumps appear. The scaly or crusty part of the bump is dry and rough. The growths start out as flat scaly areas, and later grow into a tough, wart-like area.

An actinic keratosis site commonly ranges between 2 and 6 millimeters in size, and can be dark or light, tan, pink, red, a combination of all these, or have the same pigment as the surrounding skin. It may appear on any sun-exposed area, such as the face, ears, neck, scalp, chest, backs of hands, forearms, or lips.

Classification

Actinic keratoses may be divided into the following types:[1]

  • Hyperkeratotic actinic keratosis
  • Pigmented actinic keratosis
  • Lichenoid actinic keratosis
  • Atrophic actinic keratosis

See also:

Incidence

Actinic keratosis is very common, affecting half of the global population. It is seen more often in fair-skinned individuals, and prevalence can vary with geographical location and age. People who take immunosuppressive drugs, such as organ transplant patients, are 250 times more likely to develop actinic keratoses which may lead to skin cancer[7].

Prevention

Preventive measures recommended for AK are similar to those for skin cancer:

  • Not staying in the sun for long periods of time without protection (e.g., sunscreen, clothing, hats).
  • Frequently applying powerful sunscreens with SPF ratings greater than 30 and that also block both UVA and UVB light.
  • Wearing sun protective clothing such as hats, long-sleeved shirts, long skirts, or trousers.
  • Avoiding sun exposure during noon hours is very helpful because ultraviolet light is the most powerful at that time.

According to an article in the Journal of Investigative Dermatology (2005) 125, 93–97; doi:10.1111/j.0022-202X.2005.23733.x, entitled "Human Papillomavirus-DNA Loads in Actinic Keratoses Exceed those in Non-Melanoma Skin Cancers", actinic keratosis can contain a significant amount of infectious human papillomavirus. Verbatim: "HPV presents in significantly higher viral loads in actinic keratosis (AK), which are the precursor lesions of squamous cell carcinoma (SCC), than in SCC. Viral loads of 1 HPV-DNA copy per less than 50 cells were measured in 40% of AK. The higher viral loads in AK are likely to reflect enhanced HPV-DNA replication. This may be because of intense keratinocyte proliferation and differentiation in AK favoring amplification of commensalic HPV. Active HPV replication and presumably enhanced gene expression may in turn stimulate keratinocyte proliferation and contribute to carcinogenesis in these early stages of NMSC development. HPV-E6 proteins were recently shown to inhibit UV-induced apoptosis by abrogation of Bak in response to UV damage (Jackson and Storey, 2000) and to bind a protein required for repair of single strand DNA breaks (Iftner et al, 2002). Thereby, accumulation of UV-induced mutations and oncogenic transformation might be facilitated in cases of active HPV infection."

Diagnosis

Doctors can usually identify AK by doing a thorough examination. A biopsy may be necessary when the keratosis is large and/or thick, to make sure that the bump is a keratosis and not a skin cancer. Seborrheic keratoses are other bumps that appear in groups like the actinic keratosis but are not caused by sun exposure, and are not related to skin cancers. Seborrheic keratoses may be mistaken for an actinic keratosis.

Histopathology

Actinic keratosis usually shows focal parakeratosis with associated loss of the granular layer, and thickening of the epidermis. The normal ordered maturation of the keratinocytes is disordered to varying degrees, there may be widening of the intracellular spaces, and they may also have some cytologic atypia, such as abnormally large nuclei. The underlying dermis often shows severe actinic elastosis and a mild chronic inflammatory infiltrate[6].

Treatment

Cryosurgery instrument used to treat actinic keratoses

Various modalities are employed in the treatment of actinic keratosis:

Regular follow-up after the treatment is advised by many doctors. The regular checks are to make sure no new bumps have developed and that old ones haven't become thicker.

Research

In 2007, Australia biopharmaceutical company Clinuvel Pharmaceuticals Limited began clinical trials with a melanocyte-stimulating hormone called afamelanotide (SCENESSE®)[11] (formerly CUV1647)[12] for mitigation of photodynamic therapy side effects in organ transplant patients.[13][14]

Another Australian biopharmaceutical company, Peplin,[15] is also developing a topical treatment for actinic keratosis. Formed in 1998 they are currently developing Ingenol Mebutate, which is the first in a new class of compounds and which is derived from Euphorbia peplus, or E. peplus, a rapidly growing, readily-available plant, commonly referred to as petty spurge or radium weed. The sap of E. peplus has a long history of traditional use for a variety of conditions, including the topical self-treatment of various skin disorders, such as skin cancer and pre-cancerous skin lesions. The company has recently redomiciled to the USA and is about to enter phase III trials with Ingenol Mebutate.

See also

External links

References

  1. ^ a b c Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. pp. Chapter 108. ISBN 1-4160-2999-0.{{cite book}}: CS1 maint: multiple names: authors list (link) Cite error: The named reference "Bolognia" was defined multiple times with different content (see the help page).
  2. ^ Prajapati V, Barankin B (2008). "Dermacase. Actinic keratosis". Can Fam Physician. 54 (5): 691, 699. PMC 2377206. PMID 18474700. {{cite journal}}: Unknown parameter |month= ignored (help)
  3. ^ Freedberg, et. al. (2003). Fitzpatrick's Dermatology in General Medicine. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.
  4. ^ a b Quaedvlieg PJ, Tirsi E, Thissen MR, Krekels GA (2006). "Actinic keratosis: how to differentiate the good from the bad ones?". Eur J Dermatol. 16 (4): 335–9. PMID 16935787.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. ^ "actinic keratosis" at Dorland's Medical Dictionary
  6. ^ a b c Weedon, David (2010). Weedon's Skin Pathology, 3rd Edition. Elsevier. ISBN 978-0-7020-3485-5.
  7. ^ http://www.clinuvel.com/skin-conditions/skin-cancer/actinic-keratosis
  8. ^ Ericson MB, Wennberg AM, Larkö O (2008). "Review of photodynamic therapy in actinic keratosis and basal cell carcinoma". Ther Clin Risk Manag. 4 (1): 1–9. PMC 2503644. PMID 18728698. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  9. ^ Geronemus R. "Topical Methyl Aminolevulinate Photodynamic Therapy in Patients with Multiple Actinic Keratoses: A Randomized, Double-blind, Placebo-controlled Study" J Am Acad Derm. 59(4):569-576. 2008
  10. ^ Hadley G, Derry S, Moore RA (2006). "Imiquimod for actinic keratosis: systematic review and meta-analysis". J. Invest. Dermatol. 126 (6): 1251–5. doi:10.1038/sj.jid.5700264. PMID 16557235. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  11. ^ http://www.clinuvel.com/scenesse
  12. ^ "World Health Organisation assigns CUV1647 generic name" (PDF). Clinuvel. 2008. Retrieved 2008-06-17.
  13. ^ Clinuvel » Investors » FAQs
  14. ^ Australian Life Scientist - Tackling skin cancer in organ transplant patients
  15. ^ Peplin
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