ENHANCING KIDNEY DISEASE DIAGNOSIS THROUGH BIOPSY: HISTOPATHOLOGICAL PATTERNS OF KIDNEY BIOPSIES PERFORMED IN RWANDA OVER THE PAST 4.5 YEARS.

Kidney biopsy provides essential information about the underlying pathology of both native and transplanted kidneys, allowing for accurate diagnosis and targeted management before progression to kidney failure. Despite its diagnostic value, kidney biopsy remains underutilized in many resource-limited settings due to technical, logistical, and human resource constraints.

In Rwanda, all kidney biopsies are processed and analyzed at King Faisal Hospital, Rwanda (KFHR).

To date, no published data exist on the histopathological spectrum of kidney diseases in Rwanda. Consequently, the underlying causes of non-diabetic chronic kidney disease (CKD), the predominant glomerular diseases, and the common etiologies of kidney allograft dysfunction remain poorly characterized.

This study aimed to describe the histopathological findings of kidney biopsy specimens analyzed at King Faisal Hospital, Rwanda, thereby contributing to a better understanding of kidney disease patterns and improving diagnostic precision in the Rwandan context.

A retrospective descriptive analysis was conducted on all patient records whose kidney biopsy specimens were analyzed at King Faisal Hospital, Rwanda (KFHR), between January 1, 2021, and June 30, 2025. Records with incomplete or inconsistent information, missing official pathology reports, or biopsies performed post-nephrectomy were excluded from the analysis (Figure 1).

Data were extracted using a structured data collection sheet, capturing demographic characteristics (age, sex, and area of residence), clinical indications for biopsy, and histopathological findings. Official pathology reports were reviewed and classified as native kidney biopsies or transplant kidney biopsies.

Native kidney biopsy findings were further categorized into: Glomerular diseases (e.g., minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, membranoproliferative glomerulonephritis (MPGN), etc.), Tubulointerstitial diseases, and Vascular nephropathies. Transplant kidney biopsies were grouped into: cellular, antibody-mediated rejection and transplant glomerulopathy.

Data were analyzed using IBM SPSS Statistics version 28, with descriptive statistics including mean (SD), frequencies, and percentages. Approval was obtained from KFHR IRB ref: KFH/2025/284/IRB

We retrieved a total of 150 kidney biopsies which met the eligibility criteria in the analysis (Figure 1). Over the past 4.5 years, the number of biopsy requests has steadily increased (Figure 2). The mean age of participants at the time of biopsy was 28 [±14.2] years. The majority of biopsies (78.7%) were performed on patients aged above 15 years, with a male predominance (58.0%). More than half of the participants were unemployed (59.6%), and most (75.8%) used Community-Based Health Insurance (CBHI) to cover the biopsy procedure. The main referring facilities were Kigali University Teaching Hospital (KUTH) and King Faisal Hospital, Rwanda (KFHR), contributing 44.3% and 36.9% of cases, respectively.

Approximately 90.0% of kidney biopsies were performed within 60 days of symptom onset. Of all biopsies, 12 (8.2%) were performed on kidney transplant recipients, while the remaining 138 (91.8%) were from native kidneys. The most common clinical indication for biopsy was nephrotic syndrome, with or without acute kidney injury (AKI). (Table 1)

All biopsy specimens were routinely processed. Formalin-fixed, paraffin-embedded tissue sections were prepared and stained with H&E, PAS, and Masson Trichrome and examined under the light microscope. Other fresh tissue prepared slides were stained for IgG, IgM, IgA, kappa, lambda, C1q and C3 using immunofluorescence staining. All the renal biopsies were examined by a nephropathologist. The electron microscopy facility was not available at our centre.

Immunofluorescence revealed variable patterns of immune complex deposition, with the highest positivity for IgG (31.0%) and C3 (31.9%), while IgA positivity was noted in 16.0% (n = 23) of cases. Light chain kappa, either alone or combined with lambda, was positive in 22.4% (n = 32) of cases, while lambda light chains were positive in 21.3% (n = 30) of the immunofluorescence analyses.

Among native kidney biopsies, glomerular nephropathies represented the majority of diagnosed kidney diseases. Minimal change disease (34.2%) was the most frequent histopathological diagnosis, followed by MPGN (28.4%). The predominant forms of secondary GN were lupus nephritis or post-infectious glomerulonephritis, as determined by immunofluorescence findings. More than 90.0% of the biopsies showed minimal to mild chronic changes, with <25% interstitial fibrosis and tubular atrophy (IFTA). Among transplant biopsies, cellular and antibody-mediated rejection were the most common findings. (Table 2)

This study provides the first comprehensive description of kidney biopsy findings in Rwanda. Glomerular diseases, particularly minimal change disease and membranoproliferative glomerulonephritis, were the predominant histopathological patterns among native kidney biopsies. These findings highlight the value of kidney biopsy in guiding diagnosis and management of kidney diseases and underscore the need to expand biopsy services and diagnostic capacity in Rwanda.