Precancerous Lesions Preceding Squamous Cell Carcinoma (Actinic Keratosis and Carcinoma in Situ, or Bowen's Disease)
Essentials
Actinic keratosis and carcinoma in situ (Bowen's disease) are precancerous lesions that untreated may progress to squamous cell carcinoma (SCC) Squamous Cell Carcinoma.
Exposure to UV radiation from sunlight and genetic factors play a role in its development.
Sun protection can be used to prevent or reduce the development or recurrence of precancerous lesions.
Epidemiology
Common in people with light skin, on areas exposed to sunlight, at an older age
Situated on the face (Images 12), bald scalp, upper earlobe margins, backs of the hands.
Diagnostics
The lesions are usually clearly demarcated, erythematous patches with superficial hyperkeratosis (Image 3).
The surface is usually rough on palpation, and the crust cannot be easily removed.
Hyperkeratosis may be thick and horny (cornu cutaneum; Images 456).
The diagnosis can be confirmed by skin biopsy but it is often made clinically when made by a physician with special expertise in skin cancer.
If invasive SCC is suspected, a tissue biopsy should always be taken.
This should be done if, for instance, the lesion is thick or mushy, tender on palpation or ulcerated, has grown or is pigmented, or if the patient has risk factors.
The diagnosis of precancerous lesions on the lips, i.e. actinic cheilitis (Image 7) and in situ carcinoma, should always be confirmed by biopsy.
Treatment depends on the location, size and thickness of the lesion.
Small, single precancerous lesions should primarily be treated by freezing (due to the risk of leg ulcer, in lower limbs only after due consideration). See a serious of pictures in 8.
Small precancerous lesions on the trunk and the limbs can also be treated by electrodessication or carbon dioxide laser.
Treatment of large precancerous lesions or ones situated on cosmetically visible areas:
carcinoma in situ: 5% imiquimod cream; NB: for basal cell carcinoma administration on 5 days a week for a period of 6 weeks, not an official indication.
Mushy and thick carcinoma in situ should be removed surgically with a clinical margin of 3-5 mm and a histological margin of at least 1-2 mm.
Actinic cheilitis of the lip should be treated in specialized care (by carbon dioxide laser and/or photodynamic therapy).
Follow-up examination
On control visit after treatment (e.g. at 6-12 months), the treated area is assessed by visual inspection.
It is essential that the scaling and hyperkeratosis have disappeared, and that there is no thickening or mushy feeling by palpation.
Mild erythema or hypopigmented scar (cryo- or laser therapy, electrodessication) are common findings and do not require further treatments.
Specialist consultation
In most cases, precancerous lesions can be treated by a physician familiar with such treatments in primary or outpatient care (cryotherapy, topical imiquimod cream therapy, excision of carcinoma in situ on the trunk or limbs).
Specialized care should be consulted, as necessary.
Actinic cheilitis and other precancerous lesions in the lip area should be treated in specialized care.