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| onset =
| onset =
| duration =
| duration =
| types = *Giant keratoacanthomas
| types =
* Giant keratoacanthomas
*Subungual keratoacanthoma
* Subungual keratoacanthoma
*Multiple keratoacanthomas (Ferguson–Smith syndrome)
* Multiple keratoacanthomas (Ferguson–Smith syndrome)
*Keratoacanthoma centrifugum marginatum
* Keratoacanthoma centrifugum marginatum
*Generalized eruptive keratoacanthoma of Grzybowski
* Generalized eruptive keratoacanthoma of Grzybowski
| causes =
| causes =
| risks = [[Ultraviolet radiation]], [[immunosuppression]], [[genetics]]
| risks = [[Ultraviolet radiation]], [[immunosuppression]], [[genetics]]
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| deaths =
| deaths =
}}
}}
'''Keratoacanthoma''' ('''KA''') is a common low-grade (unlikely to metastasize or invade) rapidly-growing skin tumour that is believed to originate from the hair follicle ([[pilosebaceous unit]]) and can resemble [[squamous cell carcinoma]].<ref name="Scahrf2018">{{Citation|last=Zito|first=Patrick M.|title=Keratoacanthoma|date=2018|url=http://www.ncbi.nlm.nih.gov/books/NBK499931/|work=StatPearls|volume=|pages=|publisher=StatPearls Publishing|pmid=29763106|access-date=17 September 2018|last2=Scharf|first2=Richard}}</ref><ref name="RegeziSciubba2012">{{cite book|author1=Joseph A. Regezi|author2=James Sciubba|author3=Richard C. K. Jordan|title=Oral Pathology - E-Book: Clinical Pathologic Correlations|url=https://books.google.com/books?id=bJ3Q3gN_YuYC&pg=PA155|year=2012|publisher=Elsevier Saunders|isbn=978-1-4557-0262-6|page=155|chapter=6. Neoplasms}}</ref>
'''Keratoacanthoma''' ('''KA''') is a common low-grade (unlikely to metastasize or invade) rapidly-growing skin tumour that is believed to originate from the hair follicle ([[pilosebaceous unit]]) and can resemble [[squamous cell carcinoma]].<ref name="Scahrf2018">{{Citation|last1=Zito|first1=Patrick M.|title=Keratoacanthoma|date=2018|url=https://www.ncbi.nlm.nih.gov/books/NBK499931/|work=StatPearls|publisher=StatPearls Publishing|pmid=29763106|access-date=17 September 2018|last2=Scharf|first2=Richard}}</ref><ref name="RegeziSciubba2012">{{cite book|author1=Joseph A. Regezi|author2=James Sciubba|author3=Richard C. K. Jordan|title=Oral Pathology - E-Book: Clinical Pathologic Correlations|chapter-url=https://books.google.com/books?id=bJ3Q3gN_YuYC&pg=PA155|year=2012|publisher=Elsevier Saunders|isbn=978-1-4557-0262-6|page=155|chapter=6. Neoplasms}}</ref>


The defining characteristic of a keratoacanthoma is that it is dome-shaped, symmetrical, surrounded by a smooth wall of inflamed skin, and capped with [[keratin]] scales and debris. It grows rapidly, reaching a large size within days or weeks, and if untreated for months will almost always starve itself of nourishment, [[necrosis|necrose]] (die), slough, and heal with scarring. Keratoacanthoma is commonly found on sun-exposed skin, often face, forearms and hands.<ref name="RegeziSciubba2012"/><ref>Schwartz RA. The Keratoacanthoma: A Review. J Surg Oncol 1979; 12:305–17.</ref> It is rarely found at a [[mucocutaneous junction]] or on [[mucous membranes]].<ref name="RegeziSciubba2012"/>
The defining characteristic of a keratoacanthoma is that it is dome-shaped, symmetrical, surrounded by a smooth wall of inflamed skin, and capped with [[keratin]] scales and debris. It grows rapidly, reaching a large size within days or weeks, and if untreated for months will almost always starve itself of nourishment, [[necrosis|necrose]] (die), slough, and heal with scarring. Keratoacanthoma is commonly found on sun-exposed skin, often face, forearms and hands.<ref name="RegeziSciubba2012"/><ref>Schwartz RA. The Keratoacanthoma: A Review. J Surg Oncol 1979; 12:305–17.</ref> It is rarely found at a [[mucocutaneous junction]] or on [[mucous membranes]].<ref name="RegeziSciubba2012"/>


Keratoacanthoma may be difficult to distinguish visually from a skin cancer.<ref name=Dermnetz>{{Cite web|url=https://www.dermnetnz.org/topics/keratoacanthoma/|title=Keratoacanthoma {{!}} DermNet New Zealand|last=|first=|date=|website=www.dermnetnz.org|language=en|archive-url=|archive-date=|dead-url=|access-date=17 September 2018}}</ref> Under the microscope, keratoacanthoma very closely resembles [[squamous cell carcinoma]]. In order to differentiate between the two, almost the entire structure needs to be removed and examined. While some pathologists classify keratoacanthoma as a distinct entity and not a malignancy, about 6% of clinical and histological keratoacanthomas do progress to invasive and aggressive squamous cell cancers; some pathologists may label KA as "well-differentiated squamous cell carcinoma, keratoacanthoma variant", and prompt definitive surgery may be recommended.<ref>Ko CJ, Keratoacanthoma: facts and controversies. Clin Dermatol. 2010; 28(3):254–61 ({{ISSN|1879-1131}})</ref><ref name=":0">{{Cite journal|last=|first=|date=14 August 2018|title=Keratoacanthoma: Background, Pathophysiology, Etiology|url=https://emedicine.medscape.com/article/1100471-overview|journal=Medscape|volume=|pages=|via=}}{{subscription required}}</ref><ref>Kossard S; Tan KB; Choy C; Keratoacanthoma and infundibulocystic squamous cell carcinoma. Am J Dermatopathol. 2008; 30(2):127–34 ({{ISSN|1533-0311}})</ref><ref>Weedon DD, et al. Squamous cell carcinoma arising in keratoacanthoma: a neglected phenomenon in the elderly. Am J Dermatopathol. 2010; 32(5):423–6</ref>
Keratoacanthoma may be difficult to distinguish visually from a skin cancer.<ref name=Dermnetz>{{Cite web|url=https://www.dermnetnz.org/topics/keratoacanthoma/|title=Keratoacanthoma {{!}} DermNet New Zealand|website=www.dermnetnz.org|language=en|access-date=17 September 2018}}</ref> Under the microscope, keratoacanthoma very closely resembles [[squamous cell carcinoma]]. In order to differentiate between the two, almost the entire structure needs to be removed and examined. While some pathologists classify keratoacanthoma as a distinct entity and not a malignancy, about 6% of clinical and histological keratoacanthomas do progress to invasive and aggressive squamous cell cancers; some pathologists may label KA as "well-differentiated squamous cell carcinoma, keratoacanthoma variant", and prompt definitive surgery may be recommended.<ref>Ko CJ, Keratoacanthoma: facts and controversies. Clin Dermatol. 2010; 28(3):254–61 ({{ISSN|1879-1131}})</ref><ref name=":0">{{Cite journal|date=14 August 2018|title=Keratoacanthoma: Background, Pathophysiology, Etiology|url=https://emedicine.medscape.com/article/1100471-overview|journal=Medscape}}{{subscription required}}</ref><ref>Kossard S; Tan KB; Choy C; Keratoacanthoma and infundibulocystic squamous cell carcinoma. Am J Dermatopathol. 2008; 30(2):127–34 ({{ISSN|1533-0311}})</ref><ref>Weedon DD, et al. Squamous cell carcinoma arising in keratoacanthoma: a neglected phenomenon in the elderly. Am J Dermatopathol. 2010; 32(5):423–6</ref>


== Classification ==
== Classification ==
Line 41: Line 42:
* ''Multiple keratoacanthomas'' (also known as "Ferguson–Smith syndrome," "Ferguson-Smith type of multiple self-healing keratoacanthomas,") is a cutaneous condition, a variant of keratoacanthomas, which is characterized by the appearance of multiple, sometimes hundreds of keratoacanthomas.<ref name=FITZPATRICKS2003 />{{rp|763}}<ref name=ANDREWS2005/>{{rp|644}}
* ''Multiple keratoacanthomas'' (also known as "Ferguson–Smith syndrome," "Ferguson-Smith type of multiple self-healing keratoacanthomas,") is a cutaneous condition, a variant of keratoacanthomas, which is characterized by the appearance of multiple, sometimes hundreds of keratoacanthomas.<ref name=FITZPATRICKS2003 />{{rp|763}}<ref name=ANDREWS2005/>{{rp|644}}
* A ''solitary keratoacanthoma'' (also known as "Subungual keratoacanthoma") is a benign, but rapidly growing, locally aggressive tumor which sometimes occur in the nail apparatus.<ref name=FITZPATRICKS2003 />{{rp|667,764}}<ref name=ANDREWS2005/>{{rp|644}}
* A ''solitary keratoacanthoma'' (also known as "Subungual keratoacanthoma") is a benign, but rapidly growing, locally aggressive tumor which sometimes occur in the nail apparatus.<ref name=FITZPATRICKS2003 />{{rp|667,764}}<ref name=ANDREWS2005/>{{rp|644}}
* ''Generalized eruptive keratoacanthoma'' (also known as "Generalized eruptive keratoacanthoma of Grzybowski") is a cutaneous condition, a variant of keratoacanthomas, characterized by hundreds to thousands of tiny follicular keratotic [[papule]]s over the entire body.<ref name=FITZPATRICKS2003 />{{rp|763}}<ref name=ANDREWS2005/> {{rp|645}} Treatments are not successful for many people with generalized eruptive keratoacanthoma. Use of emollients and anti-itch medications can ease some symptoms. Improvement or complete resolutions of the condition has occurred with the application of the following medications: [[acitretin]], [[isotretinoin]], [[fluorouracil]], [[methotrexate]], [[cyclophosphamide]].<ref name="GrzybowskisyndromeDermnetz">{{Cite web|url=https://www.dermnetnz.org/topics/grzybowski-generalized-eruptive-keratoacanthoma/|title=Grzybowski generalized eruptive keratoacanthomas {{!}} DermNet New Zealand|last=|first=|date=|website=www.dermnetnz.org|language=en|archive-url=|archive-date=|dead-url=|access-date=17 September 2018}}</ref>
* ''Generalized eruptive keratoacanthoma'' (also known as "Generalized eruptive keratoacanthoma of Grzybowski") is a cutaneous condition, a variant of keratoacanthomas, characterized by hundreds to thousands of tiny follicular keratotic [[papule]]s over the entire body.<ref name=FITZPATRICKS2003 />{{rp|763}}<ref name=ANDREWS2005/> {{rp|645}} Treatments are not successful for many people with generalized eruptive keratoacanthoma. Use of emollients and anti-itch medications can ease some symptoms. Improvement or complete resolutions of the condition has occurred with the application of the following medications: [[acitretin]], [[isotretinoin]], [[fluorouracil]], [[methotrexate]], [[cyclophosphamide]].<ref name="GrzybowskisyndromeDermnetz">{{Cite web|url=https://www.dermnetnz.org/topics/grzybowski-generalized-eruptive-keratoacanthoma/|title=Grzybowski generalized eruptive keratoacanthomas {{!}} DermNet New Zealand|website=www.dermnetnz.org|language=en|access-date=17 September 2018}}</ref>


== Cause ==
== Cause ==
Keratoacanthomas usually occurs in older individuals. A number of causes have been suggested including [[ultraviolet light]], chemical [[carcinogens]], recent injury to the skin, [[immunosuppression]] and [[genetic predisposition]].<ref name="Scahrf2018"/> As with squamous cell cancer, sporadic cases have been found co-infected with the [[human papilloma virus]] (HPV).<ref name=Dermnetz/><ref>Niebuhr M, et al. Giant keratoacanthoma in an immunocompetent patient with detection of HPV 11. Hautarzt. 2009; 60(3):229–32 ({{ISSN|1432-1173}})</ref> Although HPV has been suggested as a causal factor, it is unproven.<ref name="RegeziSciubba2012"/>
Keratoacanthomas usually occurs in older individuals. A number of causes have been suggested including [[ultraviolet light]], chemical [[carcinogens]], recent injury to the skin, [[immunosuppression]] and [[genetic predisposition]].<ref name="Scahrf2018"/> As with squamous cell cancer, sporadic cases have been found co-infected with the [[human papilloma virus]] (HPV).<ref name=Dermnetz/><ref>Niebuhr M, et al. Giant keratoacanthoma in an immunocompetent patient with detection of HPV 11. Hautarzt. 2009; 60(3):229–32 ({{ISSN|1432-1173}})</ref> Although HPV has been suggested as a causal factor, it is unproven.<ref name="RegeziSciubba2012"/>


Many new treatments for melanoma are also known to increase the rate of keratoacanthoma, such as the [[BRAF (gene)|BRAF]] inhibitor medications [[vemurafenib]] and [[dabrafenib]].<ref name="Niezgoda">{{cite journal |last1=Niezgoda |first1=A |title=Novel Approaches to Treatment of Advanced Melanoma: A Review on Targeted Therapy and Immunotherapy. |journal=Biomed Res Int |date=2015 |doi=10.1155/2015/851387 |pmid=26171394}}</ref>
Many new treatments for melanoma are also known to increase the rate of keratoacanthoma, such as the [[BRAF (gene)|BRAF]] inhibitor medications [[vemurafenib]] and [[dabrafenib]].<ref name="Niezgoda">{{cite journal |last1=Niezgoda |first1=A |title=Novel Approaches to Treatment of Advanced Melanoma: A Review on Targeted Therapy and Immunotherapy. |journal=Biomed Res Int |volume=2015 |date=2015 |page=851387 |doi=10.1155/2015/851387 |pmid=26171394|pmc=4478296 |doi-access=free }}</ref>


== Diagnosis ==
== Diagnosis ==
Line 52: Line 53:
Keratoacanthomas presents as a fleshy, elevated and nodular lesion with an irregular crater shape and a characteristic central hyperkeratotic core. Usually the people will notice a rapidly growing dome-shaped tumor on sun-exposed skin.<ref name="medscape.com" />
Keratoacanthomas presents as a fleshy, elevated and nodular lesion with an irregular crater shape and a characteristic central hyperkeratotic core. Usually the people will notice a rapidly growing dome-shaped tumor on sun-exposed skin.<ref name="medscape.com" />


If the entire lesion is removed, the pathologist will probably be able to differentiate between keratoacanthoma and squamous cell carcinoma. Follow-up would be required to monitor for recurrence of disease.<ref name=Baran2012>{{Cite book|url=https://books.google.co.uk/books?id=ekr4Bt683c8C&pg=PT611&dq=keratoacanthoma+removal&hl=en&sa=X&ved=0ahUKEwirpu3VscLdAhUOy4UKHY-7Av4Q6AEIJzAA#v=onepage&q=keratoacanthoma%20removal&f=false|title=Baran and Dawber's Diseases of the Nails and their Management|last=Baran|first=Robert|last2=Berker|first2=David A. R. de|last3=Holzberg|first3=Mark|last4=Thomas|first4=Luc|date=2012|publisher=John Wiley & Sons|year=|isbn=9780470657355|location=|pages=|language=en}}</ref>
If the entire lesion is removed, the pathologist will probably be able to differentiate between keratoacanthoma and squamous cell carcinoma. Follow-up would be required to monitor for recurrence of disease.<ref name=Baran2012>{{Cite book|url=https://books.google.com/books?id=ekr4Bt683c8C&q=keratoacanthoma+removal&pg=PT611|title=Baran and Dawber's Diseases of the Nails and their Management|last1=Baran|first1=Robert|last2=Berker|first2=David A. R. de|last3=Holzberg|first3=Mark|last4=Thomas|first4=Luc|date=2012|publisher=John Wiley & Sons|isbn=9780470657355|language=en}}</ref>


== Treatment ==
== Treatment ==
Excision of the entire lesion, with adequate margin, will remove the lesion, allow full tissue diagnosis, and leave a planned surgical wound which can usually be repaired with a good cosmetic result. However, removing the entire lesion (especially on the face) may present difficult problems of plastic reconstruction. (On the nose and face, [[Mohs surgery]] may allow for good margin control with minimal tissue removal, but many insurance companies require the definitive diagnosis of a malignancy ''before'' they are prepared to pay the extra costs of Mohs surgery.) Especially in more cosmetically-sensitive areas, and where the clinical diagnosis is reasonably certain, alternatives to surgery may include no treatment (awaiting spontaneous resolution).<ref name="medscape.com">Keratoacanthoma. Désirée Ratner. 2004. http://www.medscape.com/viewarticle/467069 accessed 23 June 2015</ref>
Excision of the entire lesion, with adequate margin, will remove the lesion, allow full tissue diagnosis, and leave a planned surgical wound which can usually be repaired with a good cosmetic result. However, removing the entire lesion (especially on the face) may present difficult problems of plastic reconstruction. (On the nose and face, [[Mohs surgery]] may allow for good margin control with minimal tissue removal, but many insurance companies require the definitive diagnosis of a malignancy ''before'' they are prepared to pay the extra costs of Mohs surgery.) Especially in more cosmetically-sensitive areas, and where the clinical diagnosis is reasonably certain, alternatives to surgery may include no treatment (awaiting spontaneous resolution).<ref name="medscape.com">Keratoacanthoma. Désirée Ratner. 2004. http://www.medscape.com/viewarticle/467069 accessed 23 June 2015</ref>


On the trunk, arms, and legs, [[Electrodesiccation#Electrocautery|electrodesiccation]] and [[curettage]] often suffice to control keratoacanthomas until they regress. Other modalities of treatment include [[cryosurgery]] and [[radiotherapy]]; intralesional injection of [[methotrexate]] or of [[5-fluorouracil]] have also been used.<ref name="medscape.com"/>
On the trunk, arms, and legs, [[Electrodesiccation#Electrocautery|electrodesiccation]] and [[curettage]] often suffice to control keratoacanthomas until they regress. Other modalities of treatment include [[cryosurgery]] and [[radiotherapy]]; intralesional injection of [[methotrexate]] or [[5-fluorouracil]] have also been used.<ref name="medscape.com"/>


Recurrence after electrodesiccation and curettage can occur; it can usually be identified and treated promptly with either further curettage or surgical excision.<ref name=":0" />
Recurrence after electrodesiccation and curettage can occur; it can usually be identified and treated promptly with either further curettage or surgical excision.<ref name=":0" />


==History==
==History==
In 1889, Sir [[Jonathan Hutchinson]] described a crateriform ulcer on the face”.<ref name="Fitzpatrick">{{Citation|last=Cerroni|first=Lorenzo|title=Chapter 117. Keratoacanthoma|date=2012|url=http://accessmedicine.mhmedical.com/content.aspx?aid=56059933|work=Fitzpatrick's Dermatology in General Medicine|editor-last=Goldsmith|editor-first=Lowell A.|edition=8|publisher=The McGraw-Hill Companies|access-date=2018-08-20|last2=Kerl|first2=Helmut|editor2-last=Katz|editor2-first=Stephen I.|editor3-last=Gilchrest|editor3-first=Barbara A.|editor4-last=Paller|editor4-first=Amy S.}}</ref> In 1936, the same condition was renamed "molluscum sebaceum" by MacCormac and Scarf.<ref name="Levy1954">{{Cite journal|last=Levy|first=Edwin J.|date=1954-06-05|title=Keratoacanthoma|url=https://jamanetwork.com/journals/jama/article-abstract/294464|journal=Journal of the American Medical Association|language=en|volume=155|issue=6|pages=562|doi=10.1001/jama.1954.03690240028008|issn=0002-9955}}</ref> Later, the term “keratoacanthoma” was coined by [[Walter Freudenthal]].<ref name=Hjorth1960>{{Cite journal|last=HJORTH|first=NIELS|date=August 1960|title=KERATOACANTHOMA: A HISTORICAL NOTE.|url=https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2133.1960.tb13896.x|journal=British Journal of Dermatology|language=en|volume=72|issue=8-9|pages=292–295|doi=10.1111/j.1365-2133.1960.tb13896.x|issn=0007-0963|via=}}</ref><ref name="Rook1979">{{Cite journal|last=ROOK|first=ARTHUR|last2=WHIMSTER|first2=IAN|date=January 1979|title=Keratoacanthoma–a thirty year retrospect|url=https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2133.1979.tb03568.x|journal=British Journal of Dermatology|language=en|volume=100|issue=1|pages=41–47|doi=10.1111/j.1365-2133.1979.tb03568.x|issn=0007-0963|via=}}</ref> and the term became established by [[Arthur Rook]] and the pathologist [[Ian Whimster]] in 1950.<ref name=Fitzpatrick/>
In 1889, Sir [[Jonathan Hutchinson]] described a crateriform ulcer on the face”.<ref name="Fitzpatrick">{{Citation|last1=Cerroni|first1=Lorenzo|title=Chapter 117. Keratoacanthoma|date=2012|url=http://accessmedicine.mhmedical.com/content.aspx?aid=56059933|work=Fitzpatrick's Dermatology in General Medicine|editor-last=Goldsmith|editor-first=Lowell A.|edition=8|publisher=The McGraw-Hill Companies|access-date=2018-08-20|last2=Kerl|first2=Helmut|editor2-last=Katz|editor2-first=Stephen I.|editor3-last=Gilchrest|editor3-first=Barbara A.|editor4-last=Paller|editor4-first=Amy S.}}</ref> In 1936, the same condition was renamed "molluscum sebaceum" by MacCormac and Scarf.<ref name="Levy1954">{{Cite journal|last=Levy|first=Edwin J.|date=1954-06-05|title=Keratoacanthoma|url=https://jamanetwork.com/journals/jama/article-abstract/294464|journal=Journal of the American Medical Association|language=en|volume=155|issue=6|pages=562–4|doi=10.1001/jama.1954.03690240028008|pmid=13162754|issn=0002-9955}}</ref> Later, the term “keratoacanthoma” was coined by [[Walter Freudenthal]]<ref name=Hjorth1960>{{Cite journal|last=HJORTH|first=NIELS|title=Keratoacanthoma: A Historical Note|date=August 1960|journal=British Journal of Dermatology|language=en|volume=72|issue=8–9|pages=292–295|doi=10.1111/j.1365-2133.1960.tb13896.x|s2cid=71452344|issn=0007-0963}}</ref><ref name="Rook1979">{{Cite journal|last1=ROOK|first1=ARTHUR|last2=WHIMSTER|first2=IAN|date=January 1979|title=Keratoacanthoma–a thirty year retrospect|journal=British Journal of Dermatology|language=en|volume=100|issue=1|pages=41–47|doi=10.1111/j.1365-2133.1979.tb03568.x|issn=0007-0963|pmid=427012|s2cid=27373097}}</ref> and the term became established by [[Arthur Rook (dermatologist)|Arthur Rook]] and pathologist [[Ian Whimster]] in 1950.<ref name=Fitzpatrick/>


== See also ==
== See also ==
Line 84: Line 85:
{{Skin tumors, epidermis}}
{{Skin tumors, epidermis}}


[[Category:Epidermal nevi, neoplasms, cysts]]
[[Category:Epidermal nevi, neoplasms, and cysts]]

Latest revision as of 03:34, 7 December 2023

Keratoacanthoma
Keratoacanthoma
SpecialtyDermatology, plastic surgery
Types
  • Giant keratoacanthomas
  • Subungual keratoacanthoma
  • Multiple keratoacanthomas (Ferguson–Smith syndrome)
  • Keratoacanthoma centrifugum marginatum
  • Generalized eruptive keratoacanthoma of Grzybowski
Risk factorsUltraviolet radiation, immunosuppression, genetics
Diagnostic methodTissue biopsy
Differential diagnosisSquamous cell skin cancer
TreatmentSurgery (excision, Mohs surgery)

Keratoacanthoma (KA) is a common low-grade (unlikely to metastasize or invade) rapidly-growing skin tumour that is believed to originate from the hair follicle (pilosebaceous unit) and can resemble squamous cell carcinoma.[1][2]

The defining characteristic of a keratoacanthoma is that it is dome-shaped, symmetrical, surrounded by a smooth wall of inflamed skin, and capped with keratin scales and debris. It grows rapidly, reaching a large size within days or weeks, and if untreated for months will almost always starve itself of nourishment, necrose (die), slough, and heal with scarring. Keratoacanthoma is commonly found on sun-exposed skin, often face, forearms and hands.[2][3] It is rarely found at a mucocutaneous junction or on mucous membranes.[2]

Keratoacanthoma may be difficult to distinguish visually from a skin cancer.[4] Under the microscope, keratoacanthoma very closely resembles squamous cell carcinoma. In order to differentiate between the two, almost the entire structure needs to be removed and examined. While some pathologists classify keratoacanthoma as a distinct entity and not a malignancy, about 6% of clinical and histological keratoacanthomas do progress to invasive and aggressive squamous cell cancers; some pathologists may label KA as "well-differentiated squamous cell carcinoma, keratoacanthoma variant", and prompt definitive surgery may be recommended.[5][6][7][8]

Classification

[edit]
A person with generalized eruptive keratoacanthomas

Frequently reported and reclassified over the last century, keratoacanthoma can be divided into various subtypes and despite being considered benign, their unpredictable behaviour has warranted the same attention as with squamous cell carcinoma.[1]

Keratoacanthomas may be divided into the following types:[9]: 763–764 [10]: 643–646 

  • Giant keratoacanthomas are a variant of keratoacanthoma, which may reach dimensions of several centimeters.[9]: 763 
  • Keratoacanthoma centrifugum marginatum is a cutaneous condition, a variant of keratoacanthomas, which is characterized by multiple tumors growing in a localized area.[9]: 763 [10]: 645 
  • Multiple keratoacanthomas (also known as "Ferguson–Smith syndrome," "Ferguson-Smith type of multiple self-healing keratoacanthomas,") is a cutaneous condition, a variant of keratoacanthomas, which is characterized by the appearance of multiple, sometimes hundreds of keratoacanthomas.[9]: 763 [10]: 644 
  • A solitary keratoacanthoma (also known as "Subungual keratoacanthoma") is a benign, but rapidly growing, locally aggressive tumor which sometimes occur in the nail apparatus.[9]: 667, 764 [10]: 644 
  • Generalized eruptive keratoacanthoma (also known as "Generalized eruptive keratoacanthoma of Grzybowski") is a cutaneous condition, a variant of keratoacanthomas, characterized by hundreds to thousands of tiny follicular keratotic papules over the entire body.[9]: 763 [10] : 645  Treatments are not successful for many people with generalized eruptive keratoacanthoma. Use of emollients and anti-itch medications can ease some symptoms. Improvement or complete resolutions of the condition has occurred with the application of the following medications: acitretin, isotretinoin, fluorouracil, methotrexate, cyclophosphamide.[11]

Cause

[edit]

Keratoacanthomas usually occurs in older individuals. A number of causes have been suggested including ultraviolet light, chemical carcinogens, recent injury to the skin, immunosuppression and genetic predisposition.[1] As with squamous cell cancer, sporadic cases have been found co-infected with the human papilloma virus (HPV).[4][12] Although HPV has been suggested as a causal factor, it is unproven.[2]

Many new treatments for melanoma are also known to increase the rate of keratoacanthoma, such as the BRAF inhibitor medications vemurafenib and dabrafenib.[13]

Diagnosis

[edit]
Microscopic view of a skin keratoacanthoma

Keratoacanthomas presents as a fleshy, elevated and nodular lesion with an irregular crater shape and a characteristic central hyperkeratotic core. Usually the people will notice a rapidly growing dome-shaped tumor on sun-exposed skin.[14]

If the entire lesion is removed, the pathologist will probably be able to differentiate between keratoacanthoma and squamous cell carcinoma. Follow-up would be required to monitor for recurrence of disease.[15]

Treatment

[edit]

Excision of the entire lesion, with adequate margin, will remove the lesion, allow full tissue diagnosis, and leave a planned surgical wound which can usually be repaired with a good cosmetic result. However, removing the entire lesion (especially on the face) may present difficult problems of plastic reconstruction. (On the nose and face, Mohs surgery may allow for good margin control with minimal tissue removal, but many insurance companies require the definitive diagnosis of a malignancy before they are prepared to pay the extra costs of Mohs surgery.) Especially in more cosmetically-sensitive areas, and where the clinical diagnosis is reasonably certain, alternatives to surgery may include no treatment (awaiting spontaneous resolution).[14]

On the trunk, arms, and legs, electrodesiccation and curettage often suffice to control keratoacanthomas until they regress. Other modalities of treatment include cryosurgery and radiotherapy; intralesional injection of methotrexate or 5-fluorouracil have also been used.[14]

Recurrence after electrodesiccation and curettage can occur; it can usually be identified and treated promptly with either further curettage or surgical excision.[6]

History

[edit]

In 1889, Sir Jonathan Hutchinson described a crateriform ulcer on the face”.[16] In 1936, the same condition was renamed "molluscum sebaceum" by MacCormac and Scarf.[17] Later, the term “keratoacanthoma” was coined by Walter Freudenthal[18][19] and the term became established by Arthur Rook and pathologist Ian Whimster in 1950.[16]

See also

[edit]

References

[edit]
  1. ^ a b c Zito, Patrick M.; Scharf, Richard (2018), "Keratoacanthoma", StatPearls, StatPearls Publishing, PMID 29763106, retrieved 17 September 2018
  2. ^ a b c d Joseph A. Regezi; James Sciubba; Richard C. K. Jordan (2012). "6. Neoplasms". Oral Pathology - E-Book: Clinical Pathologic Correlations. Elsevier Saunders. p. 155. ISBN 978-1-4557-0262-6.
  3. ^ Schwartz RA. The Keratoacanthoma: A Review. J Surg Oncol 1979; 12:305–17.
  4. ^ a b "Keratoacanthoma | DermNet New Zealand". www.dermnetnz.org. Retrieved 17 September 2018.
  5. ^ Ko CJ, Keratoacanthoma: facts and controversies. Clin Dermatol. 2010; 28(3):254–61 (ISSN 1879-1131)
  6. ^ a b "Keratoacanthoma: Background, Pathophysiology, Etiology". Medscape. 14 August 2018.(subscription required)
  7. ^ Kossard S; Tan KB; Choy C; Keratoacanthoma and infundibulocystic squamous cell carcinoma. Am J Dermatopathol. 2008; 30(2):127–34 (ISSN 1533-0311)
  8. ^ Weedon DD, et al. Squamous cell carcinoma arising in keratoacanthoma: a neglected phenomenon in the elderly. Am J Dermatopathol. 2010; 32(5):423–6
  9. ^ a b c d e f Freedberg, et al. (2003). Fitzpatrick's Dermatology in General Medicine. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.
  10. ^ a b c d e James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. ISBN 0-7216-2921-0.
  11. ^ "Grzybowski generalized eruptive keratoacanthomas | DermNet New Zealand". www.dermnetnz.org. Retrieved 17 September 2018.
  12. ^ Niebuhr M, et al. Giant keratoacanthoma in an immunocompetent patient with detection of HPV 11. Hautarzt. 2009; 60(3):229–32 (ISSN 1432-1173)
  13. ^ Niezgoda, A (2015). "Novel Approaches to Treatment of Advanced Melanoma: A Review on Targeted Therapy and Immunotherapy". Biomed Res Int. 2015: 851387. doi:10.1155/2015/851387. PMC 4478296. PMID 26171394.
  14. ^ a b c Keratoacanthoma. Désirée Ratner. 2004. http://www.medscape.com/viewarticle/467069 accessed 23 June 2015
  15. ^ Baran, Robert; Berker, David A. R. de; Holzberg, Mark; Thomas, Luc (2012). Baran and Dawber's Diseases of the Nails and their Management. John Wiley & Sons. ISBN 9780470657355.
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  17. ^ Levy, Edwin J. (1954-06-05). "Keratoacanthoma". Journal of the American Medical Association. 155 (6): 562–4. doi:10.1001/jama.1954.03690240028008. ISSN 0002-9955. PMID 13162754.
  18. ^ HJORTH, NIELS (August 1960). "Keratoacanthoma: A Historical Note". British Journal of Dermatology. 72 (8–9): 292–295. doi:10.1111/j.1365-2133.1960.tb13896.x. ISSN 0007-0963. S2CID 71452344.
  19. ^ ROOK, ARTHUR; WHIMSTER, IAN (January 1979). "Keratoacanthoma–a thirty year retrospect". British Journal of Dermatology. 100 (1): 41–47. doi:10.1111/j.1365-2133.1979.tb03568.x. ISSN 0007-0963. PMID 427012. S2CID 27373097.
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