Pathologic Spectrum of Kidney Disease Associated with Snake Bites

Background: Snake bites are a rare cause of acute renal failure, of which the underlying pathology is poorly understood. We present a series of 216 patients from India who developed kidney failure in temporal association with snake bites to demonstrate the spectrum of histopathologic findings in this setting Methods: Patients with history of snake bite who underwent kidney biopsy from 2013-2024 were identified from the kidney pathology archives of the Renopath Center for Renal and Urologic Pathology in Chennai, India. Demographics, laboratory values and pathologic data were reviewed Results: A total of 216 patients who underwent a kidney biopsy with history of recent snake bite were identified. Biopsies were received from 52 centers throughout India. There were 123 males(56.9%) and 93 females(43.1%), mean age was 44.7±14.3 years. All but one patient presented with acute kidney injury with a mean serum creatinine of 6.9±3.2 mg/dL. Of 216 biopsies, 211 were adequate for diagnosis. Biopsy diagnoses from this cohort of patients included acute tubular injury(ATI, n=64), acute interstitial nephritis(AIN,n=58), acute tubular injury combined with acute interstitial nephritis (ATI/AIN,n=28), renal cortical necrosis alone(n=11), thrombotic microangiopathy(TMA,n=48), mesangioproliferative glomerulonephritis(n=1), and IgA nephropathy with acute interstitial nephritis(n=1). Pigmented casts, seen in the setting of intravascular hemolysis or rhabdomyolysis, were present in 32 cases of ATI(50% of those with ATI), 9 ATI/AIN cases(32%), and 3 patients with TMA(6%). Immunohistochemical stain confirmed hemoglobin pigment in 18 and myoglobin pigment in 11 cases. Two patients with ATI had both hemoglobin and myoglobin casts. Concurrent cortical necrosis was present in 23 patients with TMA(48%). Nearly all cases were without chronic changes on biopsy. Mean global glomerulosclerosis was 7.0%. The majority of patients lacked interstitial fibrosis and tubular atrophy(no IF/TA,92.8%). Arteriosclerosis was seen in 18.1% biopsies Conclusion: The major histopathologic diagnoses in patients with acute renal failure with a recent history of snake bite, in descending order are ATI(30.3%), AIN(27.5%), TMA(22.7%), ATI/AIN(13.3%), and renal cortical necrosis(5.2%). Hemoglobin and myoglobin casts were commonly seen in ATI and AIN cases, suggesting hemolysis and/or rhabdomyolysis as etiologic drivers of disease