Primary Perinephric Abscess Caused by Mycobacterium abscessus in a Renal Transplant Recipient.

Non-tuberculous mycobacteria are increasingly recognized as opportunistic pathogens in solid organ transplant recipients, most commonly causing cutaneous, pulmonary, or disseminated disease. Primary perinephric involvement without evidence of dissemination is exceptionally rare. We report the case of a 34‑year‑old male renal transplant recipient who presented eight months post‑transplant with right iliac fossa pain and fever following minor trauma. Imaging revealed a perinephric collection initially suspected to be a hematoma. Routine bacterial cultures were sterile, and procalcitonin levels were low. Acid‑fast bacilli were detected on the smear, and mycobacterial culture identified Mycobacterium abscessus, a rapidly growing non‑tuberculous mycobacterium. The patient was successfully managed with percutaneous drainage and a tailored multidrug antimicrobial regimen, avoiding aminoglycosides to preserve graft function, although management was complicated by significant drug‑related toxicities and immunosuppressant interactions. This case highlights the importance of considering non‑tuberculous mycobacterial infection in culture‑negative perinephric collections in immunocompromised hosts and underscores the diagnostic and therapeutic challenges posed by Mycobacterium abscessus in renal transplant recipients.