Causes and pathological characteristics of native renal thrombotic microangiopathy in an Egyptian population with clinical correlation

Abstract

Introduction Thrombotic microangiopathy (TMA) in needle renal biopsy stands as one of the most important diagnostic critical values in nephropathology, and a diagnostic challenge in many of affected patients. The condition has various etiologies with different underlying pathogenetic mechanisms. The urgent handling of such cases with clinical anticipation and histopathological diagnosis draws the management and prognosis of these patients. Objectives In this paper, the histopathological characteristics of native renal TMA lesions were analyzed with determination of the possible underlying etiology and correlation with the clinical findings in Egyptian patients over a duration of 5 years. Patients and methods A retrospective study was conducted to analyze the pathological findings and clinical data of our patients with biopsy-proven renal TMA over a duration of 5 years (from January 2014 to January 2019). One hundred and twenty-seven cases were included. Results The prevalence of native renal TMA in our patients was 3.90% with male: female ratio (0.9: 1) and age range (2–80 years). The most common manifestation was acute kidney injury (64.57%). An underlying etiology was identified in 88 (69.29%) cases and the most common cause was association with autoimmune diseases (27.27%), followed by drug-induced TMA (15.91%), infection-associated TMA, and malignant hypertension (14.77% each). Acute TMA pathological features without evidence of chronicity were seen in 56 (44.09%) cases. The most encountered acute glomerular pathological lesion was irregular capillary wall thickening (68.50%), followed by tuft thrombosis (67.72%) and endothelial swelling (63.78%). Cortical necrosis was detected in 14 (11.02%) patients. The highest percentage of chronic damage features was detected in malignant hypertension and pregnancy-associated TMA. Conclusion TMA is a rare finding in needle native renal biopsy in the study’s Egyptian population with varied underlying etiological agents. The clinicopathological integration and implementing the recent clinical laboratory tests for identification of the underlying etiology of TMA has utmost importance to guide the appropriate management plan of these patients.