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

Diagnostics

• The lesions are usually clearly demarcated, erythematous patches with superficial hyperkeratosis (picture ).
• The surface is usually rough on palpation, and the crust cannot be easily removed.
• Hyperkeratosis may be thick and horny (cornu cutaneum; pictures ).
• 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.
  • Pictures
• The diagnosis of precancerous lesions on the lips, i.e. actinic cheilitis (picture ) 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.
• The primary treatment for small, single precancerous lesions in outpatient care are ointment treatments (see below) or freezing treatment where possible (due to the risk of leg ulcer, in lower limbs only after due consideration). See a series of pictures in , as well as the videos Curettage and Cryotherapy of Actinic Keratosis and Cryotherapy of Actinic Keratosis.
• Small precancerous lesions on the trunk and the limbs can also be treated by electrodessication or carbon dioxide laser.
• Treatment of large (field cancerization) precancerous lesions or ones situated on cosmetically visible areas:
  • 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.
  • fluorouracil, solution, cream or gel (special regulations may apply)
  • photodynamic therapy (PDT) (methylaminolevulinate, aminolevulinic acid) including daylight PDT (aminolevulinic acid)Photodynamic Therapy for Actinic Keratoses
• 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