Tubulointerstitial nephritis: a biopsy case series of 139 Japanese patients.

BACKGROUND: Tubulointerstitial nephritis (TIN) is an important cause of acute kidney injury (AKI) and advanced CKD. Only a limited number of studies have reported etiology-based differences in the clinical and/or histopathological properties and kidney outcomes of the biopsy-proven TIN. METHODS: Patients with biopsy-proven TIN identified from 2005 to 2016 in five hospitals were categorized based on the etiologies and were retrospectively analyzed in relation to the clinicopathological findings and kidney outcomes. RESULTS: Among 4815 biopsy cases screened, 153 Japanese TIN patients were identified, of whom 139 patients with ≥ 6 months of follow-up data (median 58 years old, 45.3% female, median 31.5 months follow-up) were further analyzed. TIN was drug-induced in 32.4%, autoimmune-related in 24.5%, of unknown etiology in 27.3% and other disease-related in 15.8%. Non-steroidal anti-inflammatory drugs and antibiotics were major causative drugs in drug-induced TIN, and IgG4-related disease, Sjögren's syndrome and sarcoidosis were common in autoimmune-related TIN. Among etiology groups, drug-induced TIN showed advanced AKI with elevated serum creatinine (sCr) and increased C-reactive protein levels at the diagnosis. TIN patients with autoimmune diseases showed less-severe AKI, but were more frequently treated with corticosteroids than others. Tubulointerstitial injury expansion in biopsy specimens was comparable among the groups. Complete or partial kidney function recovery at 6 months was more frequent in drug-induced and autoimmune-related TIN than in others. sCr levels at 6 months were similar among the groups. CONCLUSIONS: This largest case series study of the biopsy-proven TIN in Japan provides detailed information regarding both etiology-based clinicopathological properties and kidney outcomes.

A Case of Hepatic Glomerulosclerosis with Monoclonal IgA1-κ Deposits.

Glomerular immunoglobulin A (IgA) deposition is a common finding in hepatic glomerulosclerosis; thus, this disease is also called hepatic IgA nephropathy. However, only a small number of patients with hepatic IgA nephropathy have active glomerular lesions, so functional decline is slow in most cases. In this report, we describe a 60-year-old man who developed nephrotic syndrome and progressive renal impairment during follow-up for alcoholic liver cirrhosis. A renal biopsy showed a membranoproliferative glomerulonephritis-like pattern; diffuse double-contours of the glomerular basement membrane and focal active glomerular lesions with moderate-to-severe endocapillary proliferation and fibrocellular crescents. Immunofluorescence findings revealed granular staining for monoclonal IgA1-κ and C3 on the peripheral capillary walls. Laboratory examinations did not reveal any definitive evidence of myeloproliferative disorders. Therefore, this case may represent a previously unrecognized etiology of renal injury in relation to liver cirrhosis that is characterized by monoclonal IgA1-κ deposits and proliferative glomerulonephritis.