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Last updated Oct. 22, 2018

Approved by: Maulik P. Purohit MD MPH

Keratoacanthoma (KA) is a tumor of the skin (hair follicles) of low-grade malignancy that typically affects elderly men and women.

What are the other Names for this Condition? (Also known as/Synonyms)

  • KA (Keratoacanthoma)
  • Well-Differentiated SCC, KA Type
  • Well-Differentiated Squamous Cell Carcinoma, Keratoacanthoma Type

What is Keratoacanthoma? (Definition/Background Information)

  • Keratoacanthoma (KA) is a tumor of the skin (hair follicles) of low-grade malignancy that typically affects elderly men and women. Some consider it to be a variant of squamous cell carcinoma (SCC) of skin
  • Prolonged exposure to the sun’s ultraviolet rays may result in damage of skin DNA, causing the condition. Other factors that may influence its development include Muir-Torre syndrome, immunosuppression, and infection by human papilloma virus (HPV)
  • Keratoacanthomas may appear as well-defined skin nodules, commonly on the sun-exposed areas, such as the face, neck, arms, and legs. The lesions may ulcerate and cause scarring of skin
  • The treatment of choice is a surgical excision. In majority of the cases, the prognosis of Keratoacanthoma is excellent with appropriate treatment. No metastasis is observed with KA

Who gets Keratoacanthoma? (Age and Sex Distribution)

  • Keratoacanthoma generally affects older adults in the 60-70’s age group
  • It can occur in both males and females, though it is more common in males
  • The condition is generally prevalent worldwide, though dark-skinned individuals (Asians and Africans) are affected less than lighter-skinned individuals (Europeans and Americans)

What are the Risk Factors for Keratoacanthoma? (Predisposing Factors)

The risk factors for Keratoacanthoma include:

  • Exposure to intense sun (ultraviolet radiation) for long periods during the course of work or due to regular participation in outdoor sports activities
  • Frequent use of tanning beds, tanning parlors
  • People living in geographical regions where hot-dry, desert-like climatic conditions prevail
  • Muir-Torre syndrome (a genetic disorder)
  • Individuals with weak immune system, which could be due to cancer treatment, AIDS, or those on immunosuppressant drugs after receiving an organ transplant
  • HPV infection
  • Radiation therapy
  • Previous burn sites
  • Arsenic and coal tar exposure
  • Smoking and chewing of tobacco
  • Those with sensitive skin, who get easily sunburned
  • Caucasians are more vulnerable compared to other dark-skinned individuals

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Keratoacanthoma? (Etiology)

  • The cause of development of Keratoacanthoma is not well-established. It is a tumor of the squamous epithelium of skin and is believed to be linked to squamous cell carcinoma
  • Some researchers believe that it may be due to exposure to sunlight
  • Other influencing factors include human papilloma virus, trauma, and poor immunity

What are the Signs and Symptoms of Keratoacanthoma?

The signs and symptoms of Keratoacanthoma include:

  • It occurs as a well-formed nodule and is usually solitary in nature
  • The size of the lesions range from 1-2 cm
  • They grow rapidly, then stabilize in size and start to disappear
  • It may ulcerate and bleed
  • In some cases, the tumor may appear more pigmented than the surrounding skin
  • Keratoacanthomas are observed on sun-exposed areas that include the face, arms, and legs

How is Keratoacanthoma Diagnosed?

A diagnosis of Keratoacanthoma is made by:

  • Complete physical examination with detailed medical history evaluation
  • Examination by a dermatologist using a dermoscopy, a special device to examine the skin
  • Wood’s lamp examination: In this procedure, the healthcare provider examines the skin using ultraviolet light. It is performed to examine the change in skin pigmentation
  • Tissue biopsy: A biopsy of the tumor is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Keratoacanthoma?

The possible complications due to Keratoacanthoma may include:

  • Discomfort, irritability of the affected skin
  • Cosmetic issues, particularly if the nodules appear on the face. Permanent scarring might occur and cosmetic surgery may be required to restore the skin condition
  • Even though Keratoacanthomas are low-grade tumors, no metastasis is observed in them. However, the condition may recur after treatment

How is Keratoacanthoma Treated?

The treatment measures for Keratoacanthoma may include:

  • In most cases, a surgical excision and removal of the entire tumor is the preferred treatment option
  • The healthcare provider may chose to regularly monitor the tumor, if they are asymptomatic. A ‘wait and watch’ approach may be adopted
  • Follow-up care with regular screening and check-ups are important and encouraged

How can Keratoacanthoma be Prevented?

The occurrence of Keratoacanthoma may not be preventable, but the following factors may be considered to avoid its formation:

  • Avoid prolonged and chronic exposure to the sun. If this is unavoidable (like due to an occupational requirement), then take safety steps to reduce exposure to the UV rays, by using sunscreens with high sun-protection factor, using wide-brimmed hats, and protective clothing
  • Be aware of the hazards of prolonged sun exposure and take steps to protect yourself. Plan and modify your work tasks to stay out of the sun during the period, when it is the most intense
  • Avoid excessive sunbathing (particularly if you are fair-skinned), use of tanning beds, sun lamps, and chemical agents, that accelerate sun tanning
  • Individuals who are regularly exposed to the sun or work under the sun should get their skin periodically examined by a physician. This is crucial if they suspect or notice any skin changes
  • Avoid smoking and chewing of tobacco-based products
  • Treating the underlying cause for immunosuppression

What is the Prognosis of Keratoacanthoma (Outcomes/Resolutions)

  • The prognosis of Keratoacanthoma is excellent on its complete excision and removal
  • The prognosis may be dependent upon the underlying condition and health status of the individual
  • Sometimes, these tumors can recur despite treatment

Additional and Relevant Useful Information for Keratoacanthoma:

The following DoveMed website link is a useful resource for additional information:


What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

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Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Dec. 17, 2015
Last updated: Oct. 22, 2018