Although therapeutic management of hypertrophic scars and keloids using contact or spray cryosurgery has yielded significant improvement or complete regression of hypertrophic scars and keloids, it requires one to 20 treatment sessions. This study was designed to assess the clinical safety and efficacy of an intralesional needle cryoprobe method in the treatment of hypertrophic scars and keloids. Ten patients, ranging in age from 3 to 54 years, with a total of 12 hypertrophic scars and keloids of more than 6 months duration and of diverse causes, were included in this study. The 18-month trial evaluated volume reduction of the hypertrophic scars and keloids after a single session of intralesional cryotherapy. Objective (hardness and color) and subjective (pain/tenderness and itchiness/discomfort) parameters were examined on a scale of 0 to 3 (low score was better). Pretreatment and posttreatment histomorphometric studies of the collagen fibers included spectral picrosirius red polarization and fast Fourier transformation orientation index. A specially designed cryo-needle was inserted into the long axis of the hypertrophic scars and keloids so as to maximize the volume of the hypertrophic scars and keloids to be frozen. The cryo-needle was connected by an adaptor to a cryogun filled with liquid nitrogen, which was introduced into the cryoprobe, thereby freezing the hypertrophic scars and keloids. After the hypertrophic scars and keloids were completely frozen, the cryoprobe defrosted and was withdrawn. An average of 51.4 percent of scar volume reduction was achieved after one session of intralesional cryosurgery treatment (average preoperative hypertrophic scars and keloids volume, 1.82 +/- 0.33; average posttreatment volume, 0.95 +/- 0.21; p < 0.0022). Significant alleviation of objective and subjective clinical symptoms was documented. Mild pain or discomfort during and after the procedure was easily managed. Only mild local edema and epidermolysis, followed by a short reepithelialization period, were evident. During the 18-month follow-up period, there was no evidence of bleeding, infection, adverse effects, recurrence, or permanent depigmentation. The histomorphometric analysis demonstrated rejuvenation of the treated scars (i.e., parallelization) and a more organized architecture of the collagen fibers compared with the pretreated scars. This study demonstrated the increased efficacy of this method as a result of increased freezing area of deep scar material compared with that obtained with contact/spray probes. As a result, fewer treatment cycles are needed. Because the reepithelialization period is short, treatment intervals, if any, can be shortened to 2 to 3 weeks. This intralesional cryoneedle method is simple to operate and safe to use, it necessitates less postoperative care of the wound, and it can easily be added to any preexisting cryosurgical unit.

To explain the mechanism of action of a novel intralesional cryoprobe, thermal behavior measurements, and histological studies were performed in swine muscle specimens after intralesional cryosurgery ex vivo. Slow cooling (20 degrees C/min) and thawing (25 degrees C/min) rates, end temperature of -30 degrees C, produced 8 mm wide diffuse coagulative-type necrosis and a 3 mm-wide transition zone around the cryoprobe. In contrast, contact cryosurgery showed fast cooling and thawing rates (80 degrees C/min) and an end temperature of -100 degrees C. Efficacy and safety of the intralesional cryoprobe was further assessed in ten recalcitrant auricular keloids in nine Caucasian patients. There was a 67.4 +/- 23 percent reduction of scar volume at the end of the 18-month follow-up period after a single intralesional treatment (p < 0.005). Significant reduction of hardness, elevation, and redness as well as itching, pain, and tenderness was documented. The histomorphometric analysis, including spectral and fractal analysis, as well as assessment of the fast Fourier transform algorithm, showed parallel alignment and reorganization of the collagen fibers in the treated scar similar to that in the normal dermis. A long hold time in the deep scar core caused minimal damage to the superficial tissue, including melanocytes. There was no evidence of permanent hypopigmentation, active bleeding, infection, or recurrence. The major advantages of the intralesional cryoprobe, including the marked efficacy of a single treatment, may have a major importance in the clinical application of cryosurgery in the treatment of keloids and of other lesions localized deep in the skin.