Variations of symptoms of atopic dermatitis and psoriasis in relation to menstrual cycle

To the Editor: Atopic dermatitis (AD) is a multifactorial, chronic relapsing, itchy, T helper 2 (Th2)-cytokine–driven skin disease.1,2 Type 2 cytokines, including interleukin 4 (IL-4), IL-13, and IL-31, also act as master regulators of chronic itch.2 Circulating sex hormones regulate skin homeostasis; in particular, progesterone impairs skin barrier function.3 Estradiol and progesterone directly or indirectly modulate the secretion of Th2 cytokines, with higher Th2 polarization during the luteal phase and pregnancy.