IntroductionThe role of iron in, and the prognosis of, pediatric IgA nephropathy (IgAN) with macrohematuria-induced acute kidney injury (MH-AKI) have not been evaluated. Thirty percent of adults with MH-AKI, and especially those who are older, show progression to chronic kidney disease. MethodsWe evaluated the immunohistopathologic characteristics of renal biopsy samples from pediatric patients with MH-AKI IgAN and controls using Berlin Blue to identify iron, CD163 (a hemoglobin-scavenging receptor, and CD68 (a total macrophage marker), then compared the findings against the clinical characteristics of the patients. ResultsWe enrolled 44 children: 19 with IgAN but no MH or AKI, 5 with IgAN and MH but no AKI (MH(+)AKI(−) IgAN), 11 with MH-AKI IgAN, and 9 with no IgAN, MH, or AKI, according to a renal biopsy. Berlin Blue staining was detected predominantly at the injured tubulointerstitium, and the areas of staining in MH(+)AKI(−) and MH-AKI IgAN children were significantly more extensive. The areas of Berlin Blue and CD163 staining did not perfectly match, but areas of Berlin Blue were surrounded by immunopositivity for CD163. No children with MH-AKI IgAN showed decreased renal function at their last visit. ConclusionChildren with IgAN and MH, with or without AKI, showed considerable iron deposition in their renal tubules. CD163-positive cells might scavenge hemoglobin in patients with MH-AKI IgAN, but not their roles as macrophages. The renal prognosis of pediatric MH-AKI IgAN is good.