Cryobiopsy: An alternative technique to conventional shave biopsy.

To the Editor: Skin biopsies usually require local anesthetic (LA). LA can cause pain and distress especially in needle phobic individuals. Cryobiopsy is an alternative to shave biopsy under LA, in that it enables the removal of a fragment of tissue without the need for LA. In this study, we assessed the level of pain in patients undergoing skin cryobiopsy as well as the tissue usefulness for histopathological diagnosis. This was a prospective single-blinded study. All patients were older than 18 years, and written informed consent was obtained. Cryobiopsy was carried out on lesions in which shave biopsy was a diagnostic option. Patients with cold-triggered conditions were excluded. Cryobiopsies were performed using the technique that we have previously described. We sprayed liquid nitrogen onto the lesion approximately for 3 to 5 seconds, 1 to 1.5 inches away, until whitening and partially hardening of the lesion to biopsy. We then did a shave biopsy using a number 15 surgical blade while the lesion was still frozen. The sample was immediately placed in formaldehyde solution. After the procedure, patients assessed the level of pain of the freeze and cryobiopsy using an 11-point Numeric Pain Rating Scale (NPRS), where 0 equals ‘‘no pain,’’ 1 to 3 equal ‘‘mild,’’ 4 to 6 equal ‘‘moderate,’’ and 7 to 10 equal ‘‘severe pain.’’ Two pathologists with experience in diagnosing frozen biopsies analyzed the cryobiopsies independently. They were both blinded to the shave biopsy technique and were asked to comment on tissue damage or artifacts that could limit the diagnosis. A total of 270 lesions were analyzed in 258 patients (131 males, 127 females, mean age 73.67 6 12.21 years). The mean pain score of the cryobiopsy using the NPRS was 2.466 1.54 SD. Most patients (83.72%) rated the cryobiopsy as a ‘‘mildly painful’’ procedure and 16.27% classified the discomfort as ‘‘moderate.’’ No patients felt the procedure caused ‘‘severe pain’’ (Table I). None of the patients required pain relief medication and no vasovagal reactions occurred. Histopathology diagnosed 79 basal cell carcinoma, 63 squamous cells carcinoma, 14 seborrheic keratoses, 11 viral warts, 5 fibromas, 3 angiomas, and 1 nevus. No histopathological specimens showed any tissue damage or artifacts. An excellent interobserver agreement between the two pathologist was found for all the skin biopsies (kappa[0.8). An extended experience exists using the cryobiopsy in other fields of medicine, such as in interstitial lung disease. In this series, a total of 167 nonmelanoma skin cancers were confirmed using cryobiopsies without any tissue artifact that could limit interpretation. Pain associated with LA is most likely due to its acidity. Nevertheless, there are studies that propose buffering the solution before injection to reduce pain. In addition, cryoanalgesia is already used in various dermatologic procedures, including laser procedures. No comparative studies have been conducted to measure the pain of LA and cryoanalgesia. This study shows that cryobiopsy is a mildly painful and ‘‘needle-less’’ procedure. It can be safely performed in sensitive areas such as the nose and genitalia. This study also confirms that cryobiopsy does not cause any tissue damage or artifact that might make histopathological interpretation difficult.