Thrombotic Microangiopathy on Native Renal Biopsies: Unraveling the Histopathological Spectrum and Etiological Correlation in a South Indian Cohort
K. S. Vinay, N. Somanath, Mythri Shankar, Shreedhar C. Gurusiddaiah
A
BSTRACT
Background:
Thrombotic microangiopathy (TMA) is a clinicopathological entity marked by microvascular thrombosis, resulting in microangiopathic hemolytic anemia, thrombocytopenia, and end-organ injury, most commonly affecting the kidneys. Renal TMA often presents as acute kidney injury (AKI) and contributes significantly to morbidity and progression to end-stage renal disease. Given the heterogeneous etiologies and overlapping histopathological features, detailed evaluation of renal biopsies with clinicopathological correlation is essential.
Aim:
The aim of the study was to evaluate the spectrum of histopathological findings in renal biopsies diagnosed as TMA and correlate them with etiological, clinical, and laboratory parameters.
Materials and Methods:
This single-center, retrospective study included native renal biopsies diagnosed with TMA from January 2023 to June 2025. Clinical and laboratory data were obtained from medical records. Biopsies were examined by light microscopy and direct immunofluorescence. Histopathological changes were systematically analyzed.
Results:
Among 867 native renal biopsies, 44 cases (5.07%) were diagnosed with TMA. The mean age was 37.9 ± 12.8 years, with a male predominance (1.6:1). Malignant hypertension was the most common etiology (72.7%). Vascular involvement predominated (70.5%), followed by glomerular (18.2%) and combined involvement (11.4%). Acute lesions included mesangiolysis and fragmented red blood cells in the vascular lumen with mucoid intimal edema, while chronic changes included focal segmental glomerulosclerosis and vascular intimal fibrosis. Vascular mucoid intimal edema showed a significant association with malignant hypertension.
Conclusion:
Renal TMA exhibits diverse histopathological patterns, predominantly vascular, with malignant hypertension emerging as the leading etiology and a major contributor to AKI in this cohort.