A case of non-lupus full-house nephropathy diagnosed by kidney biopsy but observed IgA nephropathy on second biopsy

We describe a case of full-house nephropathy without any underlying disease, including systemic lupus erythematosus. A 40-year-old woman was referred to our hospital with mild proteinuria and microscopic hematuria. The patient was diagnosed with immune complex-mediated glomerulonephritis with a predominant mesangioproliferative pattern based on renal histopathological results using full-house immunofluorescence staining. She showed no clinical criteria for the diagnosis of systemic lupus erythematosus, except for kidney disorders, and tested negative for antinuclear antibodies throughout her clinical course. However, in the second kidney biopsy, no C1q or C4 were detected in the immunofluorescence study, suggesting an immunoglobulin A nephropathy-like pattern. The patient responded favorably to corticosteroid treatment. We found a heterozygous CFHR3-CFHR1 deletion. The association between full-house nephropathy and CFHR3-CFHR1 deletion is unknown, but its influence on the histological pattern in our case is suspected. This indicates the diversity in the pathogenesis of non-lupus full-house nephropathy and warrants further investigation.