A novel, reproducible biophysical model was developed that revealed keloid volume freezing limitations by a single needle and validates the observations of minor epidermal and deep dermal damage induced by intralesional cryosurgery, according to results from a report published in the Journal of the European Academy of Dermatology and Venereology.
Intralesional cryosurgery has been shown to be among the most effective treatment strategies for keloids; however, clinical studies have produced varying results. In this study, the researchers investigated a novel biophysical model for intralesional cryosurgery.
The impingement of intralesional cryosurgery using a Cryoshape® needle was performed on 37°C-heated potatoes, which mirrors the in vivo procedure as it exhibits identical specific heat and similar heat conductivity ashuman skin. Three studies were used to evaluate the duration of a complete potato freezing: treatment of potato for 5, 10, and 15 minutes with the surgical needle and the detection of possible differences in the frozen area, at various puncture depths.
The results revealed that no complete potato freezing resulted through a cryosurgical needle over long periods. The limited frozen tissue damage that was detected had achieved a double concave form. In addition, the freezing effect was not distributed equally; the stronger tissue damage was shown to be at the distal exit rather than the proximal entrance site. The concave form of tissue damage flattened with time at the area under the needle. Needle freezing with puncture were only seen at distances of 0.5 cm from the tissue surface but not at deeper positions of 1 and 1.5 cm, which confirms the low rates of epidermal damage and permanent depigmentation of intralesional cryosurgery.
The surface is protected from freezing by a needle positioning of deeper than 1.0 cm from the surface, the investigators found. They posited that a “single cryosurgical needle can provide satisfactory freezing to only small keloids,” and that larger and more vascular keloids may require simultaneous administration of several needles.
The authors concluded that findings provide the rationale for further experimental studies at a clinical setting in which ensuing vascular thrombosis and immunological sequelae may substantiate the clinical result.
Zouboulis VA, Zouboulis CC. A novel experimental model for studying efficacy of cryosurgery in keloids (published online on February 6, 2020). J Eur Acad Dermatol Venereol. doi:10.1111/jdv.16267