Acanthosis nigricans (AN) is a skin condition characterized by thickened, hyperpigmented plaques commonly appearing in intertriginous areas such as the neck, axillae, groin and anogenital regions.

Regarding topical treatments for AN, keratolytic is often considered the first-line option and is generally well-tolerated by children and adolescents. Topical tretinoin at concentrations of 0.25% to 0.1% has shown effectiveness in reducing hyperkeratosis and mild improvement in skin pigmentation when consistently applied. However, intermittent application for maintenance may be necessary, as relapse has been observed after discontinuation. Topical adapalene gel, available over-the-counter, has also demonstrated efficacy in reducing skin pigmentation in children with AN, with less irritation compared to other retinoid derivatives. 

Tretinoin cream, available in concentrations of 0.025% to 0.1%, is typically applied once nightly or twice daily. It is used to correct hyperkeratosis (excessive keratinization) and promote the normalization of epithelial growth and differentiation.

Over-the-counter ammonium lactate cream with lactic acid can also be applied to affected areas, and combination therapy with topical tretinoin and 12% ammonium lactate has shown efficacy in treating AN. Further combinations, such as triple therapy with tretinoin, the depigmenting agent 4% hydroquinone and 0.01% fluocinolone acetonide, may also help reduce the appearance of AN.

Urea cream, with a concentration of 7%, can be applied once daily, twice daily or three times daily as needed. It is used to promote the desquamation (shedding) of hyperkeratotic (thickened) skin and reduce excessive keratinization.

Vitamin D analogs, particularly calcipotriol cream, have been reported as safe, effective and well-tolerated options for the topical treatment of AN. Calcipotriol cream has shown a good response in treating hyperkeratosis of the nipple.

In summary, urea and tretinoin offer promising topical treatment options for managing AN. These components, either individually or in combination with other agents, have shown efficacy in reducing hyperkeratosis and improving skin pigmentation. 

Source:Pollock S, Swamy MR, Tremblay ES, Shen L. Pediatr Med 2022;5:42.