Kidney Morphology in Paediatric Mortalities Associated With Severe Acute Respiratory Illness at the Kenyatta National Teaching and Referral Hospital

Abstract

Background: Acute kidney disease in African children has been directly attributed to the high burden of infectious disease in the region. In severe infections, injury to the kidneys may arise through direct spread of causative microorganisms or indirectly through immunologic mechanisms. Acute respiratory illnesses contribute significantly to morbidity and mortality in children under the age of 5 years in Africa but accurate data on renal complications associated with these infections is extremely limited. Development of acute renal complications in children hospitalised for management of a respiratory illness may worsen the clinical course of the disease and contribute to morbidity or lead to mortality. This study described pathologic changes to the kidneys in children who died while undergoing treatment for Severe Acute Respiratory Illness (SARI) at the Kenyatta National teaching and referral Hospital (KNH). Objectives: To describe the gross and histopathologic changes to the kidneys in fatal paediatric SARI cases at KNH and corelate these changes to aetiologic agent, age, and gender. Design: A laboratory based cross-sectional descriptive study carried out from May 2017 to March 2018. Setting: The Kenyatta National Hospital and University of Nairobi histopathology laboratories. Materials and Methods: Sixty-four (64) preserved paraffin embedded tissue blocks collected from the kidneys in a previously conducted Paediatric Respiratory Surveillance Study (PRESS) at KNH were retrieved. Histologic sections from these blocks were stained using routine Haematoxylin and Eosin and special staining techniques (PAS, PASM and Masson’s Trichrome) to describe histopathologic patterns of renal pathology. The gross descriptions of the kidneys recorded at autopsy and histomorphologic features identified through conventional light microscopy were utilised together to describe a final diagnostic pattern of kidney pathology for each case. These findings were correlated with SARI aetiologic agent, age, and gender for each case. Results: All sixty-four (64) preserved kidney tissue blocks from the PRESS study were selected for review. Three (3) cases were excluded due to poor preservation and deaths 14 attributed to non-infective SARI causes, resulting in a sample size of 61 cases. The mean age was 10.7 months (SD ± 10), with an age range of 1 to 48 months, and a male to female ratio of 1:1.2. At autopsy, 19.7% of cases had abnormal morphologic appearance of the kidneys. The mean combined unfixed kidney weights in these cases were 33.5 ± 1.9gms for the right kidney and 33.1 ± 1.9gms for the left kidney. On light microscopic examination of the renal parenchyma, 98.4% of cases demonstrated glomerular pathology (DPGN 64.1%, FSGS 18%, Membranoproliferative/Membranous GN 13.1% and Crescents in 3.2%). Tubulointerstitial pathology was demonstrated in 60.6% of cases (ATN in 34.4% and focal TIN in 26.2%) while renal microvascular pathology was demonstrated in 21.1% of cases (Arteriolar arteriolosclerosis 11.5%, vascular congestion 6.3%, and thrombosis in 3.3%). There was no co relation between all histopathologic changes observed under microscopy with SARI aetiologic agent, age and gender (p = > 0.05 for bacterial, viral, fungal and protozoal infections). Conclusions: There are significant acute pathologic changes to the kidneys in fatal paediatric SARI cases in KNH. These changes are however not directly attributable to the SARI etiologic agent and are not age or gender specific. This therefore suggests that acute kidney injury in fatal paediatric SARI results from renal involvement in systemic broad spectrum immunologic assault due to overwhelming infection in these critically ill children.