Diagnosis of shunt nephritis through cerebrospinal fluid culture: avoiding the need for kidney biopsy. Illustrative case.

backgroundShunt nephritis, although rare, should be high in the differential diagnoses for patients with gross or microscopic hematuria and a history of a ventriculoatrial/cystoatrial shunt. OBSERVATIONS: The authors present the case of a 31-year-old female with a history of a resected posterior fossa hemangioblastoma and hydrocephalus, who presented to the nephrology clinic with night sweats and tea-colored urine for 3 months after being hospitalized for a saddle pulmonary embolism; kidney biopsy was contraindicated. The patient had hypocomplementemia, nephrotic-range proteinuria, positive proteinase 3-specific antineutrophil cytoplasmic antibody, and dysmorphic red blood cells in the urine sediment. CSF culture grew Propionibacterium acnes. The patient was diagnosed with shunt nephritis without the need for a kidney biopsy. The patient was treated with ceftriaxone and surgical shunt removal. Hematuria, proteinuria, and night sweats resolved 3 weeks later. A ventriculoperitoneal shunt was placed 4 months later for persistent hydrocephalus. LESSONS: Shunt nephritis is a rare type of glomerulonephritis that can progress to end-stage renal disease or death if the diagnosis is delayed or not established. Definitive treatment involves antibiotic therapy and surgical shunt removal. This case highlights that a kidney biopsy is not necessary for diagnosis in all cases, and aspiration of shunt fluid could be all that is required to determine a diagnosis. https://thejns.org/doi/10.3171/CASE24546.