Skin of color repigmentation after phenol-croton oil chemical peel

To the Editor: The history of chemical peels tells that Antoinette La Gasse, the daughter of a French physician during World War I, was one of the first phenol-croton oil operators in the United States. La Gasse, who was African American, was thought to have experimented with the formulas on herself for skin lightening,1Hetter G.P. An examination of the phenol-croton oil peel: part II. The lay peelers and their croton oil formulas.Plast Reconstr Surg. 2000; 105: 240-248Crossref PubMed Scopus (40) Google Scholar using a 47% phenol and 0.22% croton oil formula.2Rasmussen C. 1950s face peel inventor hit legal wrinkles. Los Angeles Times. https://www.latimes.com/archives/la-xpm-1999-oct-17-me-23476-story.html, 1999. Accessed July 7, 2023.Google Scholar Chemical wounding may indeed cause hypopigmentation, particularly in patients with skin of color (SOC).3Wambier C.G. Lee K.C. Soon S.L. et al.International Peeling SocietyAdvanced chemical peels: phenol-croton oil peel.J Am Acad Dermatol. 2019; 81: 327-336Abstract Full Text Full Text PDF PubMed Scopus (32) Google Scholar This understanding has driven clinical practice away from the application of such treatments in SOC. In this study, we aimed to describe the usual spontaneous repigmentation postdeep chemical peel in clinical observation of patients with Fitzpatrick V and VI and in an animal model experiment. Four black-skin domestic pigs (2 males and 2 females) had 4 cm2 areas on the back and sides peeled with Hetter’s formula containing 35% phenol and 1.6% croton oil (Delasco) and were evaluated for clinical and histologic signs of hypopigmentation to the 21st postoperative day, when 4-mm punch biopsies were taken and were compared with a negative control area (no phenol or croton oil). Ten photographs of each biopsy were analyzed at 200 × magnification through ImageJ software by 2 blinded evaluators. Melanin density in the epidermis was quantified in Fontana–Masson-stained sections. Neocollagenesis thickness was evaluated through Herovici stain. Macroscopic evaluation of the animals revealed temporary hypopigmentation on day 7, which resolved by day 21 when no clinical signs of hypopigmentation or hyperpigmentation were noticeable. Dermatopathology showed fully recovered epidermal pigmentation, albeit fewer melanosomes were noted than the negative control (Fig 1). Microscopic areas of melanophages were noted. A band of >500 μm of collagen type III was observed in all animals, revealing a satisfactory deep peel depth of injury (Supplementary Fig 1, available via Mendeley at https://doi.org/10.17632/kbzt99gwjt.1). In our clinical practice, facial repigmentation postpeel in 3 patients with Fitzpatrick V and VI occured 1-month post–full-face facial deep peel (Supplementary Figs 2 and 3, available via Mendeley at https://doi.org/10.17632/kbzt99gwjt.1). After eschar detachment, the skin appeared depigmented until day 7. On day 21, facial pigmentation was normal. In one patient subjected to more intense injury by chemabrasion postpeel (cheek acne scars at day 2), mild, localized hypopigmentation occurred as illustrated in one Fitzpatrick V (Supplementary Fig 4, available via Mendeley at https://doi.org/10.17632/kbzt99gwjt.1). The spontaneous repigmentation post–phenol-croton oil peel in SOC has not been previously described in literature. Although leukoderma and hypopigmentation are potential side effects, our translational study shows spontaneous macroscopic and microscopic repigmentation in SOC model and in a patient’s clinical evaluation. This is an important finding because the use of chemical peel treatments on SOC has been limited by concerns about scarring and hyperpigmentation. Postinjury epidermal regeneration is affected by a multitude of factors, both environmental and genetic, and hair follicle density, which plays a role in the epithelial repigmentation.4Ohyama M. Hair follicle bulge: a fascinating reservoir of epithelial stem cells.J Dermatol Sci. 2007; 46: 81-89Abstract Full Text Full Text PDF PubMed Scopus (154) Google Scholar Additionally, there are variations between skin types, such as greater presence of eumelanin in SOC, which contribute to dyschromia, and larger fibroblasts, which impact wound healing via keloidal and hypertrophic scars.5Quinonez R.L. Agbai O.N. Burgess C.M. Taylor S.C. An update on cosmetic procedures in people of color. Part 1: scientific background, assessment, preprocedure preparation.J Am Acad Dermatol. 2022; 86: P715-P725Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar We hope that this experiment and clinical observation will help to guide future research in this complex healing scenario. None disclosed.