Renal Involvement in Systemic Diseases: A 13-Year Retrospective Renal Biopsy Study in Sub-Saharan African Patients

Background: Renal involvement is a frequent and potentially severe complication of systemic diseases, particularly immune-mediated disorders. Renal biopsy remains the gold standard for diagnosing, classifying, and guiding the management of renal lesions associated with these conditions. Data from Sub-Saharan Africa remain limited. Objectives: To describe the clinical indications and histopathological spectrum of renal involvement in systemic diseases based on renal biopsy findings over a 13-year period in a tertiary referral center in Sub-Saharan Africa. Methods: We conducted a single-center retrospective observational study from January 2011 to December 2023 in a university hospital pathology center in Senegal. All patients with a known or suspected systemic disease who underwent a renal biopsy and had histologically confirmed renal involvement were included. Sociodemographic data, biopsy indications, and histopathological findings were analyzed descriptively. Results: A total of 263 patients were included, representing 7.95% of all renal biopsies performed during the study period. The mean age was 39.1 ± 12.6 years, with a female predominance (72%). Renal biopsy indications were mainly related to systemic lupus erythematosus (SLE) (65.39%), dominated by proteinuria and renal failure. In 43.34% of cases, the diagnosis of the systemic disease was established based on renal biopsy findings. Histopathologically, membranous glomerulopathy and lupus nephritis were the most frequent lesions, with a predominance of proliferative forms, particularly class IV (22.05%) and class III (11.02%). Other lesions included membranoproliferative glomerulonephritis, crescentic glomerulonephritis, amyloidosis, tubulointerstitial nephritis, and thrombotic microangiopathy. SLE was the most common underlying systemic disease (80.60%), followed by cryoglobulinemia and amyloidosis among non-autoimmune conditions. Conclusion: Renal involvement in systemic diseases exhibits a wide clinical and histological spectrum, largely dominated by lupus nephritis. Given the nonspecific clinical presentations, renal biopsy is essential for accurate diagnosis, prognostic assessment, and therapeutic decision-making. These findings highlight the importance of improving access to renal biopsy and conducting prospective studies in Sub-Saharan Africa.