The goal of this randomized intra-individual design with a split-side axillary approach is to comparing the efficacy of 0.025% tretinoin cream against a cream-based formulation in the treatment of axillary hyperpigmentation associated with acanthosis nigricans.

The main questions it aims to answer are:

• The efficacy of 0.025% tretinoin cream and cream based in the treatment of axillary hyperpigmentation associated with acanthosis nigricans.
• The safety of 0.025% tretinoin cream and cream based in the treatment of axillary hyperpigmentation associated with acanthosis nigricans.

Participants were randomly assigned to apply both 0.025% tretinoin cream and the cream-based product on opposing sides of the axillary region.

This study employed a randomized intra-individual design with a split-side axillary approach, comparing the efficacy of 0.025% tretinoin cream against a cream-based formulation. Participants were randomly assigned to apply both 0.025% tretinoin cream and the cream-based product on opposing sides of the axillary region. The efficacy of treatment was assessed by Mexameter (melanin index). The investigator's global evaluation (IGE) and parent's global evaluation (PGE) were also used to evaluate the overall success rate. The local safety was conducted for assessment of any cutaneous irritation. At each visit, the investigator graded the degrees of erythema, dryness, peeling, burning, and itching using a scale of 0 to 4. This study was followed for 4 visits, at the baseline, at week 2, 4 and 8.

Inclusion Criteria:

• The participants aged over 18 years with BMI more than 25 kg/m2, axillary hyperpigmentation associated with acanthosis nigricans

Exclusion Criteria:

• Vulnerable skin diseases
• Infectious skin diseases
• Other recent diseases involving the axillary
• Other serious medical disorders e.g. liver disease
• Any patients having received other therapies for up to 4 weeks prior to enrollment
• Photosensitive skin
• Immunocompromised host
• Pregnancy and lactation
• Receiving oral retinoids
• Axillary tattoo

In accordance with our commitment to transparency and advancing scientific knowledge, individual participant data collected during this study will be made available for sharing. The data will be accessible to qualified researchers upon request, subject to approval by the data sharing committee.

The data release will occur no later than 12 months after the publication of the primary study outcomes.

Access to the data will be granted based on a set of predefined criteria, and interested parties will be required to submit a formal request outlining the purpose of data usage and plans for analysis. A data sharing agreement may be required to ensure compliance with ethical standards and the protection of participant privacy. For inquiries or to request access to the data, please contact trees_ar@yahoo.com

They were allocated the treatment via simple randomization by a third investigator who was not involved in data collection and analysis. Participants were given unlabeled jars of the topical agents. Assessments regarding clinical efficacy will be conducted by an assessor blind to treatment allocation.