Background IgG4-related kidney disease causes renal impairment of unknown pathogenesis that may progress to kidney failure. Although ectopic germinal centers contribute to the pathogenesis of the head and neck lesions of IgG4-related disease, the presence of tertiary lymphoid tissue (TLT) containing germinal centers in IgG4-RKD has rarely been reported. Case presentation We report a 72-year-old Japanese man who had IgG4-related tubulointerstitial nephritis (TIN) with TLT formation incidentally detected in a resected kidney with mass lesion of IgG4-related ureteritis in the ureteropelvic junction. During follow-up for past surgical resection of a bladder tumor, renal dysfunction developed and a ureter mass was found in the right ureteropelvic junction, which was treated by nephroureterectomy after chemotherapy. Pathology revealed no malignancy but abundant IgG4-positive cell infiltration, obliterative phlebitis and storiform fibrosis, confirming the diagnosis of IgG4-related ureteritis. In the resected right kidney, lymphoplasmacytes infiltrated the interstitium with focal distribution in the renal subcapsule and around medium vessels without storiform fibrosis, suggesting the very early stage of IgG4-TIN. Lymphocyte aggregates were also detected at these sites and consisted of B, T, and follicular dendritic cells, indicating TLT formation. IgG4-positive cells infiltrated around TLTs. Conclusions Our case suggests that TLT formation is related with the development of IgG4-TIN and our analysis of distribution of TLT have possibility to elucidate IgG4-TIN pathophysiology.

No abstract

Patient: Male, 72-year-old Final Diagnosis: Acute kidney injury • Legionnaires’ disease • nonocclusive mesenteric ischemia • rhabdomyolysis Symptoms: — Clinical Procedure: — Specialty: Gastroenterology and Hepatology • Infectious Diseases • Nephrology Objective: Unusual clinical course Background: Legionnaires’ disease is one of the most common types of community-acquired pneumonia. It can cause acute kidney injury and also occasionally become severe enough to require continuous renal replacement therapy (CRRT). Non-occlusive mesenteric ischemia (NOMI) is a condition characterized by ischemia and necrosis of the intestinal tract without organic obstruction of the mesenteric vessels and is known to have a high mortality rate. Case Report: A 72-year-old man with fatigue and dyspnea was diagnosed with Legionnaires’ disease after a positive result in the Legionella urinary antigen test pneumonia confirmed by chest radiography and computed tomography. He developed acute kidney injury, with anuria, rhabdomyolysis, septic shock, respiratory failure, and metabolic acidosis. We initiated treatment with antibiotics, catecholamines, mechanical ventilation, CRRT, steroid therapy, and endotoxin absorption therapy in the Intensive Care Unit. Despite ongoing CRRT, metabolic acidosis did not improve. The patient was unresponsive to treatment and died 5 days after admission. The autopsy revealed myoglobin nephropathy, multiple organ failure, and NOMI. Conclusions: We report a fatal case of Legionnaires’ disease complicated by rhabdomyolysis, acute kidney injury, myoglobin cast nephropathy, and NOMI. Legionella pneumonia complicated by acute kidney injury is associated with a high mortality rate. In the present case, this may have been further exacerbated by the complication of NOMI. In our clinical practice, CRRT is a treatment option for septic shock complicated by acute kidney injury. Thus, it is crucial to suspect the presence of NOMI when persistent metabolic acidosis is observed, despite continuous CRRT treatment.