Acanthosis Nigricans project

INTERVENTION: Intervention 1: Intervention group: Acanthosis Nigricans lesions of one side of the axilla/ groin is treated with Glycolic acid 70% for 4 sessions every 2 weeks. The result of treatment is compared with initial photographies 2 weeks after the last session. Intervention 2: Intervention group: The opposite side of axilla/ groin will be treated with topical Tretinoin cream 0.05% every other night. The result of this treatment is compared with initial photographies after 8 weeks of treatment. CONDITION: Acanthosis Nigricans. ; Acanthosis nigricans PRIMARY OUTCOME: Degree of resolution of Acanthosis Nigricans lesions. Timepoint: 8 weeks after initiation of therapy and 4 treatment sessions. Method of measurement: Comparison with pre treatment photographs. INCLUSION CRITERIA: Patients with Acanthosis Nigricans lesions of axilla or neck. Patients with the informed consent for participating in the study.