A large recurrent basal cell epithelioma resolved following treatment with topically applied 1% tretinoin (vitamin A acid) ointment. The lesion had been pretreated with superficial liquid nitrogen cryotherapy eight weeks previously. Coincident with the resolution of the tretinoin-induced inflammatory reaction, a hypertrophic scar developed that involuted after nine months. A hypertrophic scar was experimentally produced on normal appearing skin by the sequential administration of cryotherapy and the topical application of tretinoin, but by neither mode of therapy alone. These findings support recent studies that show a stimulatory effect of vitamin A on fibroblastic function, as well as those that demonstrate a beneficial effect of vitamin A in the treatment of malignant tumors.
Peck GL. Hypertrophic Scar After Cryotherapy and Topical Tretinoin. Arch Dermatol. 1973;108(6):819-822. doi:10.1001/archderm.1973.01620270041010