First Report of Symmetrical Drug-related Intertriginous and Flexural Exanthema (SDRIFE or Baboon Syndrome) After Erenumab Application for Migraine Prevention

INTRODUCTION: Symmetrical drug-related intertriginous and flexural exanthema (SDRIFE), formerly also called baboon syndrome, is characterized by symmetrical erythematous rash with typical localization in the gluteal and intertriginous areas. A type IV delayed hypersensitivity immune response is thought to be responsible for its development. CGRP monoclonal antibodies (CGRP mAbs) are a new class of drugs for the prevention of migraine. We present the first case of SDRIFE occurring in temporal relation to the use of erenumab for migraine prevention. CASE: A 48-year-old female patient with migraine received erenumab 140 mg subcutaneously in the thigh area for the prevention of migraine in repetitive cycles, each 1 month apart. Initially, the patient experienced no side effects. After the third cycle, a masseuse incidentally noticed a reddish, circular rash in the buttock area during a back massage. There were no other symptoms. The skin changes resolved spontaneously. Two years later, approximately 40 h after reapplication of erenumab 140 mg, the patient experienced a severe pain in the buttock area centered over the anal crease. The area of pain extended in a circular pattern with approximately 20 cm in diameter. The pain started abruptly and reached a severe intensity within about 30 min. Sitting on the buttocks was no longer possible for the patient. There was marked allodynia and hyperpathia in the entire buttocks region. A flat, broad-based blister-like skin swelling developed in this region. The blisters began opening up on the fourth day after the onset of the skin reaction. In addition, there was a pronounced redness in the entire buttock area. Here, the patient felt a strong burning pain, similar to a scald. RESULTS: The symptoms lasted for a period of 10 days. From this point on, they fully subsided under concomitant therapy with prednisolone. CONCLUSION: SDRIFE as a rare dermatological side effect should be considered in the monitoring of skin lesions during migraine prophylaxis. In view of the high migraine prevalence, knowledge of this uncommon syndrome is important. It is crucial to recognize the relationship between the medication and the circumscribed exanthema occurring distant from the injection site.