Abstract
Hypersensitivity reaction to progesterone is rare, with less than 200 cases reported. It occurs mainly in women in their third decade of life and can have a heterogeneous presentation (cutaneous and/or systemic), with temporal relation to serum levels of progesterone. Diagnosis is based on history and physical examination, supported by skin tests. We describe the case of a woman in her late 20s with pruritic erythema on the chest that manifested in the luteal phase of the menstrual cycle, with spontaneous resolution in less than 5 days, without secondary scarring. The histological diagnosis was non-specific, with evidence of interface dermatitis, but positive skin tests supported the diagnosis of autoimmune progesterone dermatitis. It is intended to alert to the manifestations of a pathology that is rare and difficult to diagnose but with a great impact on daily life.