C1q Nephropathy in a 2-Year-Old Boy: A Case Report

Abstract

<i>Background</i>: C1q nephropathy occurs when C1q is significantly deposited in the mesangial region and systemic lupus erythematosus can be excluded as a diagnosis. <i>Clinical Description</i>: A case of a 2-year-old boy who was diagnosed with steroid-resistant C1q nephropathy. As he was initially managed as a case of idiopathic nephrotic syndrome, prednisolone was administered. However, as his condition did not improve with steroid treatment, other causes for nephrotic were considered, including infections. As it was initially refractory to steroid treatment, a cytomegalovirus infection was strongly considered. Based on the histological findings, C1q deposition was noted in the mesangium, which confirmed the diagnosis of C1q nephropathy. Cyclosporine A was initiated, which resulted in complete remission from the disease. When administering high doses of steroids, it is necessary to recognize the risk of infection. <i>Conclusion</i>: C1q nephropathy is considered to be a heterogeneous disease group from the clinicopathological point of view. In order to treat established C1q nephropathy, it is necessary to clarify the pathological significance of C1q deposition in glomeruli. As it was initially refractory to steroid treatment, CMV infection was strongly considered. When administering high doses of steroids, it is necessary to recognize the risk of infection.