(107) Sterile Intramuscular Abscess Following Intramuscular Leuprolide Acetate Injection for Endometriosis: Case Report and Review of the Literature

Background: Sterile abscess formation following leuprolide acetate injection is a rare complication that is reported in 1.5-3% of patients. This is suspected to be related to an inert polymer in the injection rather than the leuprolide itself. The objective of this case is to outline a rare side effect of intramuscular (IM) leuprolide acetate injection and review the current literature.

Case: We present the case of a 19 year old with stage IV endometriosis and a history of central precocious puberty treated with IM (gluteal) leuprolide acetate from age 9 to 11 without side effects. At age 19 she initiated IM leuprolide acetate for endometriosis; 11.25 mg in the left deltoid via standard sterile technique. For five days after her first injection, she was asymptomatic, then reported injection site edema and tenderness. Topical heat and ibuprofen were recommended. She was seen on day 11 post-injection with worsening symptoms and was treated with cephalexin, triamcinolone cream and cetirizine for possible abscess versus inflammatory reaction. On day 15 post-injection she presented to the ED with progressive edema and erythema and found to have an 8.9 x 2.0 x 1.7cm left deltoid abscess on ultrasound (Figure 1). Incision and drainage with drain placement was performed by orthopedic surgery. Wound cultures were negative, consistent with a sterile abscess. She recovered well with a small surgical scar and opted for norethindrone acetate monotherapy for endometriosis. Literature review of sterile abscess formation following leuprolide acetate revealed 11 case reports describing 17 patients. Information regarding patient characteristics and abscess management from manuscripts where the full text was available are summarized (Table 1). Injection site, route, dose, number of doses prior to abscess formation, and indication varied.

Comments: Sterile abscess formation due to leuprolide acetate injection is rare; along with physical discomfort, it can limit medication absorption and efficacy. We present a case of a patient with sterile abscess from leuprolide acetate injection severe enough to require surgical management. It is essential for providers prescribing leuprolide acetate to be aware of this potential side effect to facilitate more thorough counseling, and early diagnosis or treatment with appropriate surgical referral if indicated. On review of limited case reports, we did not identify any clear trend to guide possible superior route of administration. Not enough data exists to guide practice changes yet, but increased provider awareness may improve earlier detection and intervention.