Actinic Keratoses (Pre-Cancerous Growths) and Squamous Cell Carcinoma

1.    What are actinic keratoses, disseminated superficial actinic porokeratosis and squamous cell carcinoma?

Actinic keratoses and disseminated superficial actinic porokeratoses (DSAP) or pre-cancerous skin growths, are small, pinkish or skin-colored rough spots most commonly found on sun-exposed skin.  These lesions have the potential of becoming squamous cell carcinomas, and if not treated, these cancers can become dangerously invasive and spread to nearby lymph nodes and/or throughout the body.  Approximately 5% of actinic keratoses may evolve into squamous cell carcinoma.

2.    What do actinic keratoses, disseminated superficial actinic porokeratosis and squamous cell carcinoma look like?

Actinic keratoses appear as “sandpapery” rough pink or skin-colored growths that do not seem to heal.  They may thicken, and become “horn-like.”  Alternatively, actinic keratoses may become eroded or develop a central crust or “scab.”   A skin growth that persists as an open wound for over a month should be evaluated immediately, as it may be a squamous cell skin carcinoma.  Actinic keratoses occur mainly on the face, scalp, tips of the ears, nose, lips, backs of the hands, forearms, and DSAP also occurs most often on sun exposed skin, frequently on arms or legs, and more often in women.  If left untreated, squamous cell skin cancers may develop into large masses, and although rare, may metastasize into surrounding tissue and lead to significant disfigurement upon excision.

3.    Who gets actinic keratoses, disseminated superficial actinic porokeratosis and squamous cell carcinoma?

Actinic keratoses are relatively common, especially in middle-aged, fair-skinned adults, and rarer in African-American, Asian, or other darker skin types.  In Australia or southwestern United States, where there is more sun exposure, fair-skinned adults may develop actinic keratoses at younger ages, such as the later 20s or 30s.  Actinic keratoses occur more frequently among outdoor workers, sportspersons, and lifelong tanners.  These groups also have a higher risk of developing squamous cell skin cancers.  

4.    What causes actinic keratoses, disseminated superficial actinic porokeratosis and squamous cell carcinoma?

Actinic Keratoses are caused by exposure to ultraviolet radiation from the sun.  DNA of the skin cells is damaged and, if this damage is not repaired by the body’s innate DNA-repair system, these cells may transform into cancer.  Sun exposure / UV radiation also reduces the body’s immune system, making the skin more susceptible to damage and cancerous transformation.

5.    What triggers actinic keratoses, disseminated superficial actinic porokeratosis and squamous cell carcinoma?

There are many factors that may trigger or enable actinic keratoses and squamous cell cancers to form.  These include repeated sun or other UV exposure (such as tanning beds), chronic ulcers or burn scars, working with industrial carcinogens such as fuel oils, pitch, or tar, infection with HPV (wart) virus types 16, 18, or 31, or a compromised immune system.  The resulting actinic keratoses and squamous cell skin cancers in these individuals may be much more aggressive.

Actinic keratoses may require multiple treatments, but generally disappear after one or two treatments with liquid nitrogen cryotherapy. After freezing, a blister may form over the lesion, which may crust (scab) while healing. Rarely, a slight difference in pigmentation, either darker or lighter, may be seen after the treatment. Other treatments for these lesions include Photodynamic Therapy, in which photosensitizing medication is applied and the skin is treated under blue light or intense pulsed light laser, topical chemotherapy with prescription creams, and Laser Skin Resurfacing, in which a laser removes the outer layers of the skin.