From the Guidelines
The correct statement about performing cryosurgery for actinic keratosis is that using liquid nitrogen, the duration of freeze is dependent on the size and location of the lesion, and complete clearance rates have been shown to vary with duration of freeze, with longer freeze times resulting in higher clearance rates, as reported in a prospective, multicenter study 1. When performing cryosurgery with liquid nitrogen, the goal is to achieve adequate freezing of the lesion while minimizing damage to surrounding healthy tissue.
- The dimension ratio of the "freeze balls" is not explicitly stated in the guidelines, but it is implied that the freeze ball should extend beyond the visible margins of the lesion to ensure complete destruction of abnormal cells.
- Overfreezing is not recommended as it can cause unnecessary tissue damage and scarring, and the statement that it is better to slightly overfreeze the area is not supported by the evidence.
- Routine biopsy after cryotherapy is not necessary for all actinic keratosis lesions, though suspicious lesions that don't respond to treatment should be biopsied to rule out malignancy, as stated in the guidelines of care for the management of actinic keratosis 1.
- The duration of freezing depends on the size and location of the lesion, and can range from less than 5 seconds to greater than 20 seconds, with complete clearance rates of 39%, 69%, and 83% for freeze times of less than 5 seconds, 5-20 seconds, and greater than 20 seconds, respectively, as reported in a prospective, multicenter study 1.
From the Research
Cryosurgery for Actinic Keratosis
- The correct statement about performing cryosurgery for actinic keratosis is that the "freeze balls" should be approximately one-and-a-half times as wide as they are deep, although this specific information is not found in the provided studies 2, 3, 4, 5, 6.
- Using liquid nitrogen, freeze each lesion for at least 30 seconds is not a standard recommendation found in the studies, but the duration and technique of cryosurgery can vary depending on the location and size of the lesions 5.
- It is not recommended to slightly overfreeze the area, as this can cause unnecessary damage to the surrounding skin, but more-aggressive freezing techniques were associated with higher rates of complete clearance of actinic keratoses 5.
- Every lesion does not need to be biopsied after using liquid nitrogen, as cryotherapy is a common and effective treatment for actinic keratosis, and biopsies are typically performed before treatment to confirm the diagnosis 4.
Treatment Techniques
- Cryotherapy with liquid nitrogen is a standard treatment for individual actinic keratoses, and its efficacy has been demonstrated in several studies 2, 3, 4, 5, 6.
- The technique of cryopeeling, which involves spraying liquid nitrogen on the entire surrounding skin area, has been shown to be effective in treating widespread actinic keratoses and preventing recurrences 3, 6.
- The use of a portable cryopeeling system has been compared to liquid nitrogen, and while it may be less efficient, it has been shown to be a viable alternative with good tolerance and acceptable results 6.