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 ), bald scalp, upper earlobe margins, backs of the hands.

Diagnostics

• The lesions are usually clearly demarcated, erythematous patches with superficial hyperkeratosis (Image ).
• The surface is usually rough on palpation, and the crust cannot be easily removed.
• Hyperkeratosis may be thick and horny (cornu cutaneum; Images ).
• 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 ) and in situ carcinoma, should always be confirmed by biopsy.

Treatment Topical Creams and Cryotherapy for Actinic Keratoses

• 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 .
• 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:
  • photodynamic therapy Photodynamic Therapy for Actinic Keratoses or
  • treatment with imiquimod cream
    • actinic keratosis: 5% and 3.75% imiquimod
    • 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.

Pictures