Actinic Keratosis & Squamous Cell Carcinoma

Question 1

What are features of solar (actinic) keratosis?

Answer 1

• Most common precursor for squamous cell carcinoma (SCC)
• Found on sun-exposed sites → face, ears, hands
• Hard scaly/crusty surface
• Multiple lesions may be present
• NB. AKs on lips = “actinic cheilitis”; this term is also sometimes used to refer to an uncommon photosensitive that affects the lips

Question 2

How are actinic keratoses treated?

Answer 2

• Primarily cryotherapy
• Keratolytic creams containing 10% urea, 2 to 4% salicylic acid or 10 to 15% lactic acid to reduce scaliness
• 2 to 4 weeks of 5-fluorouracil cream applied once or twice daily - the skin will become red and inflamed - sometimes topical hydrocortisone is given following fluorouracil to help settle the inflammation
• 4 to 16 weeks of imiquimod cream applied two or three times weekly
• 3 months of topical diclofenac in hyaluran gel applied twice daily – may be used for mild AKs. Moderate efficacy but much fewer side-effects
• Ingenol mebutate gel applied for 2-3 days

Question 3

What is a cutaneous horn?

Answer 3

Cutaneous horn is the name given to a solitary horny lesion; histologically these may be reported as hyperkeratotic actinic keratosis or well differentiated squamous cell carcinoma. They are treated by local shave, curette and cautery or excision.

Question 4

What is squamous cell carcinoma in situ?

Answer 4

Squamous cell carcinoma in situ usually presents as one or more slowly enlarging erythematous scaly plaques, known as Bowen’s disease. Histologically, atypical keratinocytes are found throughout the epidermis without invasion through the basement membrane.

Treated surgically mainly. Other: cryotherapy, 5-fluorouracil cream, imiquimod cream or photodynamic therapy

Question 5

What are features of squamous cell carcinoma?

Answer 5

• Arises within an AK or within SCC in situ
• Occurs in males chronically exposed to sun
• More frequent in smokers
• A locally invasive malignant tumour of epidermal keratinocytes or its appendages
• Potential to metastasise (but uncommon)

Question 6

What are risk factors for SCC?

Answer 6

• XS UV exposure
• pre-malignant skin conditions (AK)
• Chronic inflammation (eg. leg ulcers, wound scars)
• Immunosuppression
• Genetic predisposition

Question 7

What is the presentation of SCC?

Answer 7

• Keratotic (eg. scaly, crusty) ill-defined nodule
• OR firm erythematous plaque
• Frequently ulcerates

Question 8

What is the management of SCC?

Answer 8

• Nearly always treated surgically
• Wide margins advisable (if tumour >20mm then margins should be 6mm, if <20mm then 4mm margins) for poorly differentiated or anaplastic tumours
• Mohs micrographic surgery → for ill-defined, large recurrent tumours
• Radiotherapy → for large, non-resectable tumours

Question 9

What determines a good prognosis over a bad prognosis for SCC?

Answer 9