Grade 3 Dermatitis Secondary to Two Aromatase Inhibitors in Early Hormone Receptor-Positive Breast Cancer: A Case Report

Aromatase inhibitors (AIs) are widely used in the treatment of hormone receptor-positive breast cancer (HR+BC). AIs reduce the risk of HR+BC recurrence and improve disease-free survival (DFS) compared with other endocrine therapies (ETs). We report a rare case of an early, severe dermatological adverse event (dAE) to two AIs in a pre-menopausal patient receiving adjuvant treatment for human epidermal growth factor receptor 2 negative (HER2-) HR+BC. The patient developed a grade 3 eruptive, maculopapular dermatitis to exemestane and subsequently letrozole. The rash was poorly responsive to conservative management and only resolved following withdrawal of the AI. Unusually, a third AI - anastrozole - has been well tolerated. Severe dAEs secondary to AIs are rare, and there is a lack of evidence-based research to guide management of these reactions.