Abstract
Iatrogenic Cushing syndrome can occur due to the use of external glucocorticoids. We present a case involving prolonged exposure to glucocorticoids from intramuscular dexamethasone injections, with diagnosis confirmed via abscess fluid analysis. This underscores the importance of considering altered pharmacokinetics when faced with unexplained hypercortisolism. A 46-year-old woman experienced hypertension, weakness, edema, and increasing abdominal striae over 6 months. Her history included undocumented intramuscular injections for back pain a year earlier, which resulted in bilateral gluteal abscesses. Laboratory results showed suppressed morning cortisol and adrenocorticotrophic hormone levels, while imaging ruled out structural abnormalities. Although serum tests were negative, liquid chromatography-mass spectrometry performed on abscess fluid detected dexamethasone (81.1 nmol/L), confirming iatrogenic Cushing syndrome. This case highlights how local tissue changes, such as abscesses, can significantly modify glucocorticoid pharmacokinetics, creating a prolonged reservoir effect and sustained systemic exposure lasting more than a year after injection. Overall, atypical pharmacokinetics are important in cases of unexplained hypercortisolism, especially when local tissue alterations influence drug absorption and clearance. Analyzing collections like abscess fluid can provide vital diagnostic clues in complex suspected cases of iatrogenic Cushing syndrome.