Sterile abscess formation in response to two separate branded long-acting gonadotropin-releasing hormone agonists

Background: Long-acting forms of gonadotropin-releasing hormone (GnRH) receptor agonists are commonly used for the treatment of central precocious puberty (CPP). Sterile abscess formation has been reported as a complication of leuprolide acetate, but not histrelin acetate. Objective: The aim of this study was to report an adverse drug reaction in a child with sterile abscess formation following treatment with 2 different branded long-acting forms of GnRH agonists. Case summary: An otherwise healthy 8-year-old white female (weight, 40.7 kg; height, 140.1 cm) with documented CPP and no known drug allergies developed a sterile abscess at the site of the monthly intramuscular injection of 15 mg of leuprolide acetate. Because of this site reaction, a 50-mg histrelin acetate insert was placed in the patient's left arm. A similar reaction occurred 2 weeks after insert placement on 2 separate occasions in different arms. At the time of the removal of the second insert, Gram stain and swab culture of the purulent wound discharge were negative. The child was subsequently treated with intranasal nafarelin (800 ug twice daily) and tolerated it well. The Naranjo Adverse Drug Reaction Causality Score was 10 (definite, ≥9). Conclusion: This report describes a case of sterile abscess formation definitely associated with 2 different forms of long-acting GnRH agonist treatment in a child.