Evaluating the Safety and Efficacy of Topical Sirolimus 0.2% to Treat Acanthosis Nigricans

Inclusion Criteria: * Men and women ages 18+. * Clinical diagnosis of acanthosis nigricans. * Available and willing to comply with study instructions and attend all study visits. * Able and willing to provide written and verbal informed consent. Exclusion Criteria: * Subject has any skin pathology or condition that could interfere with the evaluation of the test products or requires the use of interfering topical or systemic therapy. * Subject has any condition which, in the investigator's opinion, would make it unsafe for the subject to participate in this research study. * Pregnant, lactating, or is planning to become pregnant during the study. * Subject is currently enrolled in an investigational drug or device study. * Subject has received an investigational drug or has been treated with an investigational device within 30 days prior to the initiation of treatment (baseline). * Subject is unable to communicate or cooperate with the investigator due to language problems, poor mental development, or impaired cerebral function. * Subject has known hypersensitivity or previous allergic reaction to any of the active or inactive components of the test articles. * Subject has the need or plans to be exposed to artificial tanning devices or excessive sunlight during the trial. * Erosions, ulcers, or other skin lesions within or closely neighboring the AN lesion application site. * Hypersensitivity reactions such as anaphylaxis or angioedema to sirolimus or any component of sirolimus 0.2% topical gel (HYFTOR). * Dyslipidemia (cholesterol level \>300mg/dL or \>7.75mmol/L, triglyceride level \>300 mg/dL or \>3.42 mmol/L). * Subject cannot agree to take appropriate contraception for the duration of the study and 12 weeks after the final dose. * Exclusions apply to those who have used the following topical treatments to treat AN: retinoids, hydroquinones, corticosteroids, or other depigmenting agents within one month prior to the study, or oral retinoids within six months prior to the study, or medications with mammalian target of rapamycin(mTOR) inhibitory action within 12 months prior to the first visit. * Subjects with a malignant tumor