Immunoglobulin A nephropathy in horseshoe kidney: case reports and literature review.

Horseshoe kidney is the most common congenital renal fusion anomaly. Immunoglobulin A nephropathy is a common glomerulonephritis worldwide. However, the co-occurrence of these diseases had not been reported in the literature. We report the first two cases with the occurrence of immunoglobulin A nephropathy in horseshoe kidney. The first case was a 26-year-old male with hypertension and proteinuria (1.4 g/24 h), his pathological finding was primary immunoglobulin A nephropathy. The second case was a 15-year-old female who presented with recurrent peliosis on bilateral lower extremities, haematuria and proteinuria (1.7 g/24 h). Her renal biopsy finding was Henoch-Schonlein purpura nephritis (secondary immunoglobulin A nephropathy). In both cases, renal biopsy was performed by experienced doctors under ultrasonic guidance at the renal upper pole and no postoperative complications were observed. After they were treated based on the renal pathological findings for 6 months, urine protein excretion decreased significantly and blood pressure and serum creatinine stabilized. It is possible that immunoglobulin A nephropathy occurs in a horseshoe kidney patient. Renal biopsy may be valuable and viable for horseshoe kidney patients with heavy proteinuria to identify pathologic type of glomerulopathy and to guide treatment, if renal biopsy is performed by experienced doctors at the renal upper pole under renal ultrasonic guidance.