Histopathological analysis of the therapeutic response to cryotherapy with liquid nitrogen in patients with multiple actinic keratosis

Abstract

Actinic keratoses are premalignant lesions of the skin caused by excessive sun exposure. Lesions may become mainly squamous cell carcinoma. Cryotherapy with liquid nitrogen is one of the main treatments. In order to evaluate the response of actinic keratosis to cryotherapy by histopathology, two lesions were selected in each of 14 patients with multiple actinic keratoses. In one lesion a biopsy was performed and in the other lesion a biopsy was performed after cryotherapy. Subsequently, both biopsies were compared histologically. Of the thirteen patients who completed the study, the best results were obtained in lesions undergoing cryotherapy concerning the atypia of keratinocytes, epithelial thickness and corneal layer and lymphocytic infiltrate. Despite the small number of patients, it was concluded that, if performed correctly, cryotherapy has high efficacy in the treatment of actinic keratoses.

Actinic keratosis – review for clinical practice

“…The potential to transform into squamous cell carcinomas (SCC), the second most common type of cancer of the skin, is of great concern . In many cases, AKs are subclinical and disseminated; therefore, the term field cancerization is nowadays more appropriate to describe the lesions .…”

“…In many cases, AKs are subclinical and disseminated; therefore, the term field cancerization is nowadays more appropriate to describe the lesions . Though it has no mortality, it is an important target for research and treatment because of its high incidence and difficulty in establishing which lesions with precancerous potential will progress to malignancy . The main etiological factor for SCC is the accumulation of UV damage.…”

“…Cryotherapy is the freezing of the lesion by direct application of liquid nitrogen or eventually other cryogens using a cryospray, catheter, or swab with subsequent thawing. Between −40 and −50 °C, skin keratinocytes are destroyed and nitrogen continues to be applied until approximately −196 °C for efficient extermination . The treatment regimens used range from 5 to 15 seconds of application; however, for thick lesions it may take up to 30 seconds.…”

“…For complete eradication of AKs, it is important to achieve a margin of 2–4 mm freezing around the target lesion. Therefore, a determining factor in the success of the treatment will be the ability to visualize the lesion …”

“…The procedure's advantage is its nondependence on the patient's adherence. Its efficacy ranges from 75 to 99% and is directly related to the way the application is performed …”