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'''Keratoacanthoma''' (KA) is a common low-grade (unlikely to metastasize or invade) skin tumour that is believed to originate from the neck of the ].<ref>Fisher, B.K., Elliot, G.B. Keratoacanthoma: Reflections on an Unusual Lesion. Can Med Assoc J. 1965 August 7; 93(6): 272–273.</ref> Many pathologists consider it to be a form of ] (SCC).<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> The pathologist often labels KA as "well-differentiated squamous cell carcinoma, keratoacanthoma variant", because about 6% of KA manifest itself as squamous cell carcinoma when left untreated.<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> KA is commonly found on sun-exposed skin, and often is seen on the face, forearms and hands.<ref>Schwartz RA. The Keratoacanthoma: A Review. J Surg Oncol 1979; 12:305–17.</ref> '''Keratoacanthoma''' (KA) is a common low-grade (unlikely to metastasize or invade) skin tumour that is believed to originate from the neck of the ].<ref>Fisher, B.K., Elliot, G.B. Keratoacanthoma: Reflections on an Unusual Lesion. Can Med Assoc J. 1965 August 7; 93(6): 272–273.</ref> Many pathologists consider it to be a form of ] (SCC).<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> Pathologists may label KA as "well-differentiated squamous cell carcinoma, keratoacanthoma variant", because about 6% of keratoacanthomas manifest themselves as squamous cell carcinoma when left untreated.<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> KA is commonly found on sun-exposed skin, and often is seen on the face, forearms and hands.<ref>Schwartz RA. The Keratoacanthoma: A Review. J Surg Oncol 1979; 12:305–17.</ref>


The defining characteristic of KA is that it is dome-shaped, symmetrical, surrounded by a smooth wall of inflamed skin, and capped with keratin scales and debris. It always grows rapidly, reaching a large size within days or weeks, and if untreated will starve itself of nourishment, necrose (die), slough, and heal with scarring. While some pathologists classify KA as a distinct tumor and not a malignancy, enough clinical and histological KA do progress to invasive and aggressive squamous cell cancers, therefore prompt and aggressive treatment is required.<ref>Ko CJ, Keratoacanthoma: facts and controversies. Clin Dermatol. 2010; 28(3):254–61 (ISSN: 1879-1131)</ref><ref>http://www.emedicine.com/derm/topic206.htm</ref> The defining characteristic of KA 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. While some pathologists classify KA as a distinct entity and not a malignancy, some clinical and histological keratoacanthomas do progress to invasive and aggressive squamous cell cancers, therefore prompt and definitive treatment may be recommended.<ref>Ko CJ, Keratoacanthoma: facts and controversies. Clin Dermatol. 2010; 28(3):254–61 (ISSN: 1879-1131)</ref><ref>http://www.emedicine.com/derm/topic206.htm</ref>


Under the microscope, keratoacanthoma very closely resembles squamous cell carcinoma. In order to differeniate between the two, almost the entire structure needs to be removed and examined.
In reality, the defining characteristics of a KA can not be found when only a small fragment of a large KA is submitted for pathology review. If the keratin debris is submitted, no diagnosis can be made. If a deep core or peripheral deep wedge is performed, a squamous cell carcinoma is often noted. Only when almost the entire structure is submitted, can a true diagnosis of a KA be made. This further complicates the distinction between a clinical diagnosis of a KA and the pathologic diagnosis of a KA vs a squamous cell cancer.


== Classification == == Classification ==
Keratoacanthomas (molluscum sebaceum) may be divided into the following types:<ref name=FITZPATRICKS2003>Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.</ref>{{rp|763–764}}<ref name=ANDREWS2005>James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Saunders. ISBN 0-7216-2921-0.</ref>{{rp|643–646}} Keratoacanthomas (molluscum sebaceum) may be divided into the following types:<ref name=FITZPATRICKS2003>Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.</ref>{{rp|763–764}}<ref name=ANDREWS2005>James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Saunders. ISBN 0-7216-2921-0.</ref>{{rp|643–646}}


* ''Giant keratoacanthomas'' are a cutaneous condition, a variant of keratoacanthomas, which in some instances may reach dimensions of several centimeters.<ref name=FITZPATRICKS2003 />{{rp|763}} * ''Giant keratoacanthomas'' are a variant of keratoacanthoma, which may reach dimensions of several centimeters.<ref name=FITZPATRICKS2003 />{{rp|763}}
* ''Keratoacanthoma centrifugum marginatum'' is a cutaneous condition, a variant of keratoacanthomas, which is characterized by multiple tumors growing in a localized area.<ref name=FITZPATRICKS2003 />{{rp|763}}<ref name=ANDREWS2005/>{{rp|645}} * ''Keratoacanthoma centrifugum marginatum'' is a cutaneous condition, a variant of keratoacanthomas, which is characterized by multiple tumors growing in a localized area.<ref name=FITZPATRICKS2003 />{{rp|763}}<ref name=ANDREWS2005/>{{rp|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.<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 ]s over the entire body.<ref name=FITZPATRICKS2003 />{{rp|763}}<ref name=ANDREWS2005/> {{rp|645}} Treatments are not successful for many patients 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:{{Citation needed|date=August 2013}} ], ], ], ], ] The epidemiology of Generalized eruptive keratoacanthoma remains unknown. {{Citation needed|date=August 2013}} * ''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 ]s over the entire body.<ref name=FITZPATRICKS2003 />{{rp|763}}<ref name=ANDREWS2005/> {{rp|645}} Treatments are not successful for many patients 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:{{Citation needed|date=August 2013}} ], ], ], ], ].


== Cause == == Cause ==
The tumors usually occur in older individuals. Like squamous cell cancer, data suggests ultraviolet light from the sun causes the development of KA.<ref name="pmid14871228">{{cite journal |author=Schwartz RA |title=Keratoacanthoma: a clinico-pathologic enigma |journal=Dermatol Surg |volume=30 |issue=2 Pt 2 |pages=326–33; discussion 333 |date=February 2004 |pmid=14871228 |doi= 10.1111/j.1524-4725.2004.30080.x|url=http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=1076-0512&date=2004&volume=30&issue=2%20Pt%202&spage=326}}</ref> Just like its close relative, the squamous cell cancer, sporadic cases have been found co-infected with the human papilloma virus (HPV).<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> The tumors usually occur in older individuals. As with squamous cell cancer, it seems likely that ultraviolet light from the sun causes the development of KA.<ref name="pmid14871228">{{cite journal |author=Schwartz RA |title=Keratoacanthoma: a clinico-pathologic enigma |journal=Dermatol Surg |volume=30 |issue=2 Pt 2 |pages=326–33; discussion 333 |date=February 2004 |pmid=14871228 |doi= 10.1111/j.1524-4725.2004.30080.x|url=http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=1076-0512&date=2004&volume=30&issue=2%20Pt%202&spage=326}}</ref> As with squamous cell cancer, sporadic cases have been found co-infected with the human papilloma virus (HPV).<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>


== Diagnosis == == Diagnosis ==
Diagnosis is best done with clinical exam and history. It presents as a fleshy, elevated and nodular lesion with an irregular crater shape and a characteristic central hyperkeratotic core. Usually the patient will notice a rapidly growing dome-shaped tumor on sun-exposed skin.{{uncited|date=October 2013}} Keratoacanthoma presents as a fleshy, elevated and nodular lesion with an irregular crater shape and a characteristic central hyperkeratotic core. Usually the patient will notice a rapidly growing dome-shaped tumor on sun-exposed skin.{{uncited|date=October 2013}}


] ]
If the entire lesion is removed, the pathologist will probably be able to differentiate between keratoacanthoma and squamous cell carcinoma. If only part of the lesion is removed, confident diagnosis may be impossible.
A ] must be performed to confirm the diagnosis. Unfortunately, a shave biopsy will often reveal only keratin fragments. A deep punch biopsy will often reveal a well differentiated, mildly atypical, squamous cell suggestive of an actinic keratosis or a squamous cell carcinoma. Only when the pathologist has access to the entire lesion (not practical in many circumstances) can a correct diagnosis be made. From a practical standpoint (insurance reimbursement), the correct diagnosis should be "well differentiated squamous cell carcinoma, keratoacanthoma variant". This is especially important for facial and nasal KA's, as it allows the surgeon to treat the tumor with the proper respect it deserves, with margin-controlled surgery like ].
Correct diagnosis often requires communication between the surgeon and the pathologist. Many pathologists are still under the impression that keratoacanthomas are benign growths that do not require surgery. Unfortunately, when the lesion appears on the nose, face, or hands it often grows to marble or golf ball size before necrosing, and leaving a sizable crater in the process. From a practical standpoint, the correct diagnosis of low grade squamous cell carcinoma should be rendered after communication between the surgeon and pathologist, as the tumor is often much more aggressive and the morbidity is much higher than the relatively benign ].{{uncited|date=October 2013}}


== Treatment == == Treatment ==
On the trunk, arms, and legs, ] and ] often suffice. Excision of the entire lesion is often required if one wants to confirm the clinical diagnosis of keratoacanthoma. On the nose and face, ] allows for good margin control with minimal tissue removal; unfortunately, many insurance companies require the correct diagnosis of a malignancy before allowing such procedure. Recurrence after electrodesiccation and curettage is common, and usually can be identified and treated promptly with either further curettage or surgical excision. Allowing the KA to grow and necrose spontaneously is not acceptable in today's standard of care. {{uncited|date=October 2013}} 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, ] may allow for good margin control with minimal tissue removal, but many insurance companies require the correct diagnosis of a malignancy <i>before</i> 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>Keratoacanthoma. Désirée Ratner. 2004. http://www.medscape.com/viewarticle/467069 accessed 23 June 2015</ref>

EDC, as mentioned above, has a high rate of recurrence and studies have shown the potential for transformation into more aggressive species of SCC not unlike Marjolin's ulcer. This can occur with management of BCC as well. These facts alone should call in to question the use of EDC as a management method in favor of surgical excision, especially considering cosmesis and post procedure wound care and healing.
On the trunk, arms, and legs, ] and ] often suffice to control keratoacanthomas until they regress. Other modalities of treatment include ] and ]; intralesional injection of ] or of ] have also been used.<refKeratoacanthoma. Désirée Ratner. 2004. http://www.medscape.com/viewarticle/467069 accessed 23 June 2015</ref>

Recurrence after electrodesiccation and curettage is common, and usually can be identified and treated promptly with either further curettage or surgical excision.


== See also == == See also ==

Revision as of 11:13, 23 June 2015

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Medical condition
Keratoacanthoma
SpecialtyOncology, dermatology Edit this on Wikidata

Keratoacanthoma (KA) is a common low-grade (unlikely to metastasize or invade) skin tumour that is believed to originate from the neck of the hair follicle. Many pathologists consider it to be a form of squamous cell carcinoma (SCC). Pathologists may label KA as "well-differentiated squamous cell carcinoma, keratoacanthoma variant", because about 6% of keratoacanthomas manifest themselves as squamous cell carcinoma when left untreated. KA is commonly found on sun-exposed skin, and often is seen on the face, forearms and hands.

The defining characteristic of KA 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. While some pathologists classify KA as a distinct entity and not a malignancy, some clinical and histological keratoacanthomas do progress to invasive and aggressive squamous cell cancers, therefore prompt and definitive treatment may be recommended.

Under the microscope, keratoacanthoma very closely resembles squamous cell carcinoma. In order to differeniate between the two, almost the entire structure needs to be removed and examined.

Classification

Keratoacanthomas (molluscum sebaceum) may be divided into the following types:

  • Giant keratoacanthomas are a variant of keratoacanthoma, which may reach dimensions of several centimeters.
  • Keratoacanthoma centrifugum marginatum is a cutaneous condition, a variant of keratoacanthomas, which is characterized by multiple tumors growing in a localized area.
  • 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.
  • A solitary keratoacanthoma (also known as "Subungual keratoacanthoma") is a benign, but rapidly growing, locally aggressive tumor which sometimes occur in the nail apparatus.
Picture of the face of a patient Generalized eruptive keratoacanthomas
  • 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. Treatments are not successful for many patients 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.

Cause

The tumors usually occur in older individuals. As with squamous cell cancer, it seems likely that ultraviolet light from the sun causes the development of KA. As with squamous cell cancer, sporadic cases have been found co-infected with the human papilloma virus (HPV).

Diagnosis

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

Skin keratoacanthoma whole slide

If the entire lesion is removed, the pathologist will probably be able to differentiate between keratoacanthoma and squamous cell carcinoma. If only part of the lesion is removed, confident diagnosis may be impossible.

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 correct 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).

On the trunk, arms, and legs, electrodesiccation and curettage often suffice to control keratoacanthomas until they regress. Other modalities of treatment include cryosurgery and ]; intralesional injection of methotrexate or of 5-fluorouracil have also been used.<refKeratoacanthoma. Désirée Ratner. 2004. http://www.medscape.com/viewarticle/467069 accessed 23 June 2015</ref>

Recurrence after electrodesiccation and curettage is common, and usually can be identified and treated promptly with either further curettage or surgical excision.

See also

References

  1. Fisher, B.K., Elliot, G.B. Keratoacanthoma: Reflections on an Unusual Lesion. Can Med Assoc J. 1965 August 7; 93(6): 272–273.
  2. Kossard S; Tan KB; Choy C; Keratoacanthoma and infundibulocystic squamous cell carcinoma. Am J Dermatopathol. 2008; 30(2):127–34 (ISSN: 1533-0311)
  3. Weedon DD, et al. Squamous cell carcinoma arising in keratoacanthoma: a neglected phenomenon in the elderly. Am J Dermatopathol. 2010; 32(5):423–6
  4. Schwartz RA. The Keratoacanthoma: A Review. J Surg Oncol 1979; 12:305–17.
  5. Ko CJ, Keratoacanthoma: facts and controversies. Clin Dermatol. 2010; 28(3):254–61 (ISSN: 1879-1131)
  6. http://www.emedicine.com/derm/topic206.htm
  7. ^ Freedberg, et al. (2003). Fitzpatrick's Dermatology in General Medicine. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.
  8. ^ James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. ISBN 0-7216-2921-0.
  9. Schwartz RA (February 2004). "Keratoacanthoma: a clinico-pathologic enigma". Dermatol Surg. 30 (2 Pt 2): 326–33, discussion 333. doi:10.1111/j.1524-4725.2004.30080.x. PMID 14871228.
  10. Niebuhr M, et al. Giant keratoacanthoma in an immunocompetent patient with detection of HPV 11. Hautarzt. 2009; 60(3):229–32 (ISSN: 1432-1173)
  11. Keratoacanthoma. Désirée Ratner. 2004. http://www.medscape.com/viewarticle/467069 accessed 23 June 2015
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