Horseshoe perianal abscess with deep gluteal extension managed by multi-incision and ultrasound-guided catheter drainage: a case report.

Perianal abscesses are common anorectal infections typically confined to superficial spaces, but deep extension into adjacent compartments is rare and often underdiagnosed due to subtle early symptoms. We report a 68-year-old man with a complex horseshoe perianal abscess that extended into the deep gluteus maximus. Initial drainage targeted the anorectal spaces based on clinical and magnetic resonance imaging findings, yet postoperative fever and persistent pain prompted repeat imaging, which revealed a deep gluteal abscess. Ultrasound-guided catheter drainage was performed successfully without complications. This case illustrates an unusual pathway of infection spread from the anal gland through the intersphincteric space and ischiorectal fossae into the gluteal compartment. Contributing factors included delayed presentation, malnutrition, and immunosuppression. Comprehensive assessment, multidisciplinary management, and image-guided intervention were essential for a successful outcome. Clinicians should suspect deep gluteal extension in patients with persistent systemic signs despite perianal drainage to avoid diagnostic delay and improve outcomes.