A 17-year-old male came to the emergency room after being treated with cryotherapy for recalcitrant plantar warts the day before. He had been treated on the right great toe and the medial aspect of the left great toe. The night prior there had been small blisters around both treated areas. The next morning he had significant blistering and some pain with walking. He had cut out part of his tennis shoe to accommodate the blister with much pain relief. The past medical history was non-contributory and his tetanus shot was current.
The pertinent physical exam showed a healthy male in no distress unless he was walking or pressure was placed on the left foot lesion. The right great toe lesion was unchanged from the previous night and was about 5-7 mm across that coincided with the verrucous tissue with a small amount of clear fluid in the blister. There was minimal pain. The left foot lesion was about 3 cm across and 1 cm elevation with dark fluid (see Figure 124a). The tissue around the blister was slightly erythematous but there was no cyanosis. He had normal sensation in the areas around the lesions and was able to move his toes fully.
The diagnosis of localized frostbite (grade II-III) was made. The surgical resident was consulted and after discussion with the attending and the parents who were both nurses it was decided to not disrupt the blister and treat it conservatively with rest, elevation and pain management. He and his parents were instructed to loosely cover the blister with a non-adherent bandage (antibiotic ointment with loose gauze) and to monitor it closely for extension of the lesion and infection. He returned to the surgical clinic for followup. At 1 week followup the pain was greatly diminished but there continued to be some hemorrhagic fluid. At 2-3 weeks, the fluid had mostly dissipated and he was wearing normal shoes (see Figure 124b). At 4.5 weeks, the top of the blister separated by itself from the healthy healing underlying tissue (see Figure 124c).
Figure 124a – Verrucous lesion 24 hours after treatment with cryotherapy with blistered extension of the treatment area.
Figure 124b – Resolving frostbite after 2-3 weeks.
Figure 124c – Healing granulated tissue after 4.5 weeks>
Veruccae plantaris or plantar warts are caused by Human Papillomavirus which causes benign epidermal tumors that often have a cauliflower pattern on the foot that may be elevated or flush with the surrounding skin. Lesions may resemble calluses but the normal footprint pattern is disrupted. The lesions often have pinpoint hemorrhages that appear as black dots. In an immunocompetent individual, the lesions usually have spontaneous resolution within 2 years but the infection may spread to create additional lesions. The lesions may also cause pain or discomfort because of their size or location.
There are numerous potential treatments for common warts. A 2012 Cochrane Collaboration evaluation found salicylic acid to be better than placebo especially for hand lesions. Cryotherapy overall for all sites was not better than control, but for hands may have slightly better outcomes. More aggressive cryotherapy was more effective than gentle cryotherapy but had increased side effects.
In general, cryotherapy for verrucous lesions tries to include the actual lesion and a 1-2 mm halo of normal tissue around the lesion. Even with professional equipment it still can be difficult to control the precise application of the cryotherapy to the verrucous lesions because of the lesion location, lesion depth, width of the liquid nitrogen spray from the applicator, and the length of time the cryotherapy is applied. Cryotherapy application by cotton bud is more precise as it is a direct application but it does not freeze more than ~ 3 mm in depth. Spray application, especially a longer application time, has a better chance of getting deeper into the tissues to destroy the verrucae but increases the risks of side effects. Cryotherapy is known to have higher incidence of side effects than other types of verrucous lesion treatments. Side effects include burning, pruritus, pain, erythema, and blister formation. Frostbite is also a potential complication and can occur with professional or over-the-counter cryotherapy devices.
Burns are caused by direct chemical, electrical, radiation or thermal sources resulting in tissue injury. Most people view burns as caused by heat injuries but cold application can also cause injuries by direct damage to cells, and progressive dermal ischemia. It is the dermal ischemia which is usually more harmful. When frostbite is first seen it can be difficult to estimate its severity. Frostbite is categorized after rewarming into 4 categories:
- Grade 1 – Superficial with central area of pallor and area of erythema/edema. Usually has no sequelae.
- Grade 2 – Large blisters with clear fluid with surrounding erythema/edema. Usually occurs within 24 hours of the injury. Blisters slough off with healthy granulation tissue. Heals very well.
- Grade 3 – Smaller hemorrhagic blisters with escars that form over several weeks. Damage is deeper and may have long term sequelae.
- Grade 4 – Frostbite that extends to muscle and bone with tissue necrosis. Mummification occurs in 4-10 days.
Prevention is always better than treatment. Treatment for frostbite includes treating the entire individual especially when hypothermia and other injuries are concomitant. Wet clothing should be removed and the area rewarmed with body temperature or slightly warmer water (do not use stoves/fire as the tissue is insensate and these can cause additional thermal injury). This usually takes 15-30 minutes and can be quite painful so pain management is needed. Areas should not be rubbed and walking or movement should be limited as appropriate. Wound care includes using non-adherent dressings, sterile fluffed gauze, inserting pledgets between digits to prevent maceration as appropiate and avoiding occlusive dressings. Protection from additional mechanical damage is also important. Blister treatment is controversial depending on the type of blister and location. Some recommend draining, debriding and bandaging while others recommend aspiration only or leaving them intact. Tetanus prophylaxis is recommended and prophylactic antibiotics are also controversial. Especially in the cases of severe injury, imaging studies may help determine the extent of tissue damage and response to treatment, and other treatment includes thrombolysis or vasodilitation for severe injuries.
Questions for Further Discussion
1. What are risk factors for frostbite?
2. In addition to frostbite, what are other cold-related disease processes?
- Symptom/Presentation: Vesiculobullous Lesions
- Age: Teenager
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Sammut SJ, Brackley PT, Duncan C, Kelly M, Raraty C, Graham K. Frostbite following use of a commercially available cryotherapy device for the removal of viral warts. Dermatol Online J. 2008 Jun 15;14(6):9.
Dall’oglio F, D’Amico V, Nasca MR, Micali G. Treatment of cutaneous warts: an evidence-based review. Am J Clin Dermatol. 2012 Apr 1;13(2):73-96.
Kwok CS, Gibbs S, Bennett C, Holland R, Abbott R. Topical treatments for cutaneous warts. Cochrane Database Syst Rev. 2012 Sep 12;(9):CD001781.
Sarwar U, Tickunas T. Frostbite developing secondary to cryotherapy for viral warts. Br J Gen Pract. 2013 May;63(610):239-40.
Hutchison RL. Frostbite of the hand. J Hand Surg Am. 2014 Sep;39(9):1863-8.
Zafren K. Frostbite. UpToDate. (rev. 2/15/18, cited 8/27/18).
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa