A 36-year-old dark pigmented man complained of light spots and scars following treatment of multiple hand warts with liquid nirtogen. Cryotherapy using liquid nitrogen (temperature –196C) involves the use of a cryospray, cryoprobe or a cotton-tipped applicator. The nitrogen is applied to the skin lesion for a few seconds, depending on the desired diameter and depth of freeze. The treatment is repeated in some cases, once thawing has completed. This is known as a ‘double freeze-thaw’ and is usually reserved for skin cancers or resistant viral warts.
The wart is frozen with liquid nitrogen repeatedly, at one to three week intervals. Success is in the order of 70% after 3-4 months of regular freezing. Debate on whether a light freeze to stimulate immunity is sufficient, or whether a harder freeze is necessary to destroy all the infected skin.
One of complication with cryosurgery may result in a white mark (hypo-pigmentation) or a scar, particularly when freezing has been deep or prolonged, as is required for a cancerous lesion. A white mark may sometimes follow a light freeze. The white mark may be quite noticeable especially in those with darker complexions. Although the appearance often improves with time, the colour change can be permanent.
2-3 mm hypopigmented atrophic and hypertrophic papules