Pediatric IgA-Dominant Infection-Related Glomerulonephritis

The concept of infection-related glomerulonephritis (IRGN) has been introduced as adults diagnosed with glomerulonephritis often have coexisting active infections. Furthermore, IgA-dominant IRGN is associated with staphylococcal infections in adults with comorbidities, which often progress to end-stage renal disease. Little is known about IgA-dominant IRGN in children, and no consensus for a management strategy of this condition has been reached. We describe the case of a 9-year-old boy with IgA-dominant IRGN that was diagnosed using specific staining for nephritis-associated plasmin receptor (NAPlr)/plasmin activity and galactose-deficient IgA1 (Gd-IgA1), a marker of IgA nephropathy. The patient was successfully treated using a combination of prednisolone, mizoribine (an immunosuppressive drug), and lisinopril (an angiotensin-converting enzyme inhibitor) and three courses of methylprednisolone pulse therapy. The patient was admitted to our hospital with generalized edema, gross hematuria, proteinuria, hypertension, and renal dysfunction. Hypocomplementemia contributed to a diagnosis of IRGN, although the causative organism was unknown. A renal biopsy performed when the patient presented with nephrotic syndrome showed IgA deposition, positive staining for NAPlr, and negative staining for Gd-IgA1, in addition to findings consistent with IRGN, leading to a pathologic diagnosis of IgA-dominant IRGN. The histological staining for NAPlr/plasmin activity and Gd-IgA1, together with clinical symptoms, could be helpful for diagnosing IgA-dominant IRGN. Our findings indicate that otherwise healthy children can also develop IgA-dominant IRGN. Therefore, early diagnosis and aggressive treatment should be considered when IgA-dominant IRGN is suspected to avoid the possibility of incomplete recovery of renal function.