Simultaneous Occurrence of Collagen Type III Glomerulopathy and Immunoglobulin A Nephropathy: A Rare Case Report

BACKGROUND Collagen type III glomerulopathy (CG) is a rare disease with poorly understood pathogenesis, usually identified by abnormal collagen type III accumulation in glomeruli and manifesting as progressive deterioration of kidney function with nephrotic-range proteinuria. Immunoglobulin A nephropathy (IgAN) is the most prevalent glomerulopathy worldwide and is a leading cause of end-stage renal disease as a result of progressive fibrotic changes. Fibrosis is primarily caused by collagen type III deposition, which may explain the simultaneous occurrence of IgAN and CG. CASE REPORT A young man presented with clinical and laboratory evidence of chronic kidney injury, including long-term nephrotic-range proteinuria and microscopic hematuria. Partial improvement in proteinuria was achieved with steroid therapy and conservative management. As the non-invasive workup was inconclusive, and a complete recovery of kidney function was not achieved, a kidney biopsy was done. Histopathological microscopic examination revealed advanced IgA nephropathy, Oxford classification M0E1S1T2C0, with features highly suggestive of type III collagen glomerulopathy. CONCLUSIONS We described a case of collagen type III glomerulopathy, also known as collagenofibrotic glomerulopathy, and its association with concurrent immunoglobulin A nephropathy in a healthy man presenting with chronic proteinuria and microscopic hematuria. As the number of reported cases in the Middle East is rising, we present this report to improve understanding and greater recognition of such cases.