D1.20 - Progesterone-Induced Urticaria: Diagnostic and Therapeutic Approach

A 43-year-old female patient with a history of rhino-conjunctivitis and moderate asthma, sensitized to dust mites and cat epithelium. The patient presented with pruritic wheal-like lesions that worsened with pressure, occurring 2-3 times per week. She began immunotherapy in 2022 following a pregnancy in 2021.

In November 2021, the patient experienced a spontaneous abortion. In 2023, she began developing transient wheal-like lesions just before menstruation and during periods of stress, which she managed with antihistamines, although without significant improvement.

Due to the lack of improvement and the clear worsening of the urticaria, it was decided to perform a Prick test with 0.1 ml undiluted and intradermal testing with medroxyprogesterone at concentrations of 1:10 and 1:1. The result of the Prick test was positive at 30 minutes, with a 2 mm wheal and erythema. The intradermal test with medroxyprogesterone at 1:10 showed a 3 mm wheal at 20 minutes post-test. Upon performing the intradermal test with medroxyprogesterone at 1:1, the patient experienced pruritus and erythema on the palms and dorsum of the hands, which resolved after treatment with antihistamines. Imaging was performed with the patient's informed consent.

Based on these results, the study was considered positive, and it was decided not to proceed with intramuscular provocation. The patient was referred to the Gynecology department for further evaluation and treatment with oral contraceptives that inhibit ovulation in order to block the mechanisms that cause elevated progesterone levels during the second phase of the menstrual cycle. Currently, oral contraceptives are considered first-line treatment for such conditions.