STEROIDAL AND NONSTEROIDAL AROMATASE INHIBITORS INDUCED DERMATITIS- A CASE REPORT OF CROSS-REACTIVITY

Abstract

<h3>Introduction</h3> Aromatase inhibitors (AI) are an important adjuvant therapy used in estrogen receptor-positive (ER+) breast cancer. There are two major classes: nonsteroidal (Anastrozole and Letrozole) and steroidal (Exemestane). Cutaneous reactions are treated with discontinuation of the culprit medication and switching to a different class. We describe a unique case of reaction to both classes of AI. <h3>Case Description</h3> 51-year-old woman with history of papillary thyroid carcinoma and ER+ ductal breast carcinoma presented with 2-month history of pruritus without rash after starting Anastrazole. Laboratory studies were normal. She was started on high dose antihistamines with resolution. Two months later pruritus recurred and she developed an erythematous papulovesicular rash all over the trunk. She was treated with oral steroids. Anastrazole was stopped with significant resolution of symptoms within two weeks. She was started on Exemestane with recurrence of rash and pruritus in three weeks. The medication was stopped with resolution and the patient is now doing well on Tamoxifen. <h3>Discussion</h3> Literature on AI induced cutaneous reactions is scarce. Pathogenesis is poorly understood. Symptom onset ranges from 5 days to 6 months. Morphology of cutaneous reactions includes vasculitis, erythema nodosum, and subacute cutaneous lupus. Diagnosis is clinical and treatment includes discontinuation of the offending agent. Topical and systemic immunosuppressants have been used to control symptoms. Switching to a different class of AI is recommended. To our knowledge this is the first patient reported in literature to have reacted to both classes of AI. Further studies are required to determine the best alternative agents for such patients.