Derm Dx: Hyperpigmented, hyperkeratotic papules covered by waxy scale

A moderately obese 40-year-old white woman presents with a long-standing history of an intermittently pruritic rash affecting her chest and the flexural and anogenital regions. Over the years, the eruption has waxed and waned in intensity, worsening in the summer months. Multiple topical medications have provided little relief. Several other family members are similarly affected. The dermatitis is characterized by ...