Revised 4 March 2005
Actinic keratosis do not require referral to the Agency and are normally managed by the primary care physician or by a dermatologist. Actinic keratosis are premalignant lesions and may develop into in situ or invasive squamous carcinomas. Appropriate treatment modalities include topical 5-fluorouracil therapy, liquid nitrogen cryotherapy, light electro-fulguration, and infrequently, surgical excision. If 5-fluorouracil therapy is used, the treatment course can be repeated at intervals of a few months until all dysplastic tissue has been removed. See sunscreen use (2).
Carcinoma In Situ (Including Bowen's Disease)
After a biopsy, these lesions are usually treated by surgical excision. In difficult cases, referral for specialist opinions or to the Skin Management Clinic is recommended. For the management of gynecologic cases see the section on Gynecology in this Manual.
Invasive Squamous Cell Carcinoma
Squamous cell carcinoma can be either a slowly evolving lesion arising from a long standing actinic keratosis or a rapidly growing lesion with a high metastatic potential. Immuno-suppressed patients are particularly at risk for rapidly growing and potentially metastatic SCC. Review more frequently. All squamous carcinomas should be treated promptly by surgical excision with an adequate margin or by radiation therapy. A pathology report including the words "anaplastic," "poorly differentiated," or "neurotropism" suggests a lesion at increased risk for recurrence or metastasis. In small circumscribed lesions, a margin of 5 mm is usually adequate. Referral to a surgeon, dermatologist, or to the Skin Management Clinic is recommended. If surgery will result in significant disfigurement, the Skin Management Clinic would be pleased to review the patient since radiation therapy may be preferable.
It is recommended that invasive squamous cell carcinoma not be treated with curettage and electro-fulguration, cryotherapy or topical 5-fluorouracil, as it is not possible to be sure of adequacy of removal of the squamous cell carcinoma with these modalities. In those instances where a lesion thought to be a basal cell carcinoma is treated with electro-fulguration and curettage and later is found to be a well differentiated squamous cell carcinoma, the dermatologist may elect to follow the lesion closely and treat with surgical excision or radiation therapy only if necessary. If the histology is other than well differentiated or it was a very rapidly enlarging "acute" lesion, further surgery or radiation therapy should be arranged for the patient. Rapidly enlarging squamous carcinomas even with a well differentiated histology should be treated aggressively and require close follow-up.
Squamous cell carcinomas of the skin may metastasize to regional lymph nodes.
Patients with squamous cell carcinoma of the skin should have their regional lymph nodes assessed by their physician at their initial presentation and at each follow-up visit.
Basosquamous growth patterns are normally consistent with basal cell carcinomas with squamous metaplasia (i.e. they usually behave like basal cell carcinomas). However, these lesions should be reviewed and clarified by a pathologist.
Squamous cell carcinoma of the lip is discussed under the Head and Neck section.