Minimal change disease (MCD) is a common cause of nephrotic syndrome and typically responds well to glucocorticoid therapy. Although spontaneous remission is considered rare, its true frequency may be underestimated, possibly due to the early initiation of treatment in most cases. We report a case of a 45-year-old male who developed nephrotic syndrome following an influenza infection. A kidney biopsy revealed findings consistent with minimal change disease, including diffuse foot process effacement, and proteinuria resolved spontaneously without immunosuppressive therapy. The patient remained in remission for approximately four and a half months until he developed a non-influenza upper respiratory infection, which was followed by a relapse of nephrotic syndrome. Subsequently, glucocorticoid therapy was initiated, resulting in a prompt remission. This case highlights the potential for spontaneous remission in MCD, particularly in the context of infection, and underscores the immunological heterogeneity of the disease. We also review previously reported adult cases of infection-associated spontaneous remission of MCD.

Minimal change nephrotic syndrome (MCNS) is characterized by podocyte injury leading to severe proteinuria, mainly mediated by T-cell activation and cytokine imbalance. Relapses are often triggered by immunological stimuli such as infections, vaccinations, or drugs; however, relapse following administration of sulfamethoxazole-trimethoprim (ST) combination therapy has not been reported previously. We report an extremely rare case of MCNS relapse triggered by ST combination therapy.A 55-year-old woman with a history of breast cancer treated with tamoxifen developed nephrotic syndrome and was diagnosed with MCNS by renal biopsy. After remission was achieved with prednisolone 50mg/day, ST therapy was initiated for prophylaxis of Pneumocystis jirovecii pneumonia. Approximately 12days after starting ST, she developed generalized erythema accompanied by relapse of nephrotic syndrome. Discontinuation of ST, atorvastatin, and esomeprazole while continuing prednisolone 40mg/day led to a second remission. Drug-induced lymphocyte stimulation tests for all agents were negative, possibly due to concurrent corticosteroid therapy.Metabolites of sulfamethoxazole have been shown to activate CD4+ T cells and induce multiple cytokines including interleukin-13, interferon-γ, interleukin-22, and granzyme B. Such immune activation could explain the simultaneous occurrence of cutaneous manifestations (drug eruption) and renal relapse (MCNS).Relapse of drug-induced MCNS may occur through either direct podocyte injury or immune-mediated allergic mechanisms. Given the concurrent drug eruption, the latter mechanism appears most consistent with this case.When introducing new medications under immunosuppressive conditions, clinicians should consider the possibility of drug-induced relapse if proteinuria reappears.

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is characterized by renal tubular and interstitial abnormalities and slow progressive loss of kidney function. Patients with ADTKD rarely progress to kidney failure in early childhood. A 7-year-old Japanese girl was admitted to the hospital due to afebrile seizures and was later diagnosed with Panayiotopoulos syndrome. Blood examinations showed that she had a serum creatinine level of 1.57mg/dL (Cr-eGFR 28 mL/min/1.73m²), consistent with chronic kidney disease stage 4. Ultrasonography showed bilateral small to normal-sized kidneys, with increased renal parenchymal echogenicity, poor corticomedullary differentiation, and small cysts. A panel exome sequencing targeting 187 genes identified a de novo pathogenic variant c.172G > T, p.Gly58Cys in the EGF-like domain 1 of the UMOD gene. Her parents did not possess this variant, leading to the diagnosis of a sporadic case of ADTKD-UMOD. Variants in the EGF-like domain 1 may lead to early progression to kidney failure. ADTKD-UMOD should be listed as a differential diagnosis of progressive kidney failure in early childhood, even in the absence of a family history.

Goreisan is an herbal medicine that regulates water metabolism, exerting a diuretic effect that does not alter urine volume in dehydrated conditions but increases urine output in edematous conditions without affecting plasma electrolyte levels, thereby demonstrating an anti-edema action. We report a case of severe lupus nephritis (LN) accompanied by nephrotic syndrome (NS) in which Goreisan proved effective in managing intractable edema. Goreisan is considered potentially beneficial for controlling intractable edema associated with nephritic NS, including severe LN.

Aortic thrombosis is a rare but life-threatening condition. It typically presents with abdominal or lower-limb ischemia. Although acute kidney injury (AKI) can accompany aortic thrombosis, AKI as the sole clinical manifestation has not been previously reported. A 69-year-old man with extensive atherosclerotic disease and chronic kidney disease presented with severe oliguria. Initial evaluation, including non-contrast computed tomography (CT), did not reveal any aortic abnormalities. Renal Doppler ultrasonography findings and markedly elevated D-dimer levels prompted contrast-enhanced CT, which demonstrated extensive thrombus formation extending from the descending thoracic aorta to the bilateral iliac arteries, with complete occlusion of both renal arteries and major abdominal branches. Despite widespread occlusion, the patient exhibited no abdominal or limb ischemic symptoms, likely owing to well-developed collateral circulation. Subsequently, the patient developed persistent anuria requiring hemodialysis and died on day 17. Autopsy confirmed extensive subacute aortic thrombosis, occlusion of the renal artery, and preserved intestinal mucosa consistent with collateral perfusion. We describe an exceptionally rare autopsy-confirmed case of aortic thrombosis in a case that presented solely with AKI and lacked any abdominal or limb ischemic symptoms. This case highlights the importance of considering aortic thrombosis in unexplained AKI cases. Our findings support the judicious use of contrast-enhanced CT in patients with suspected life-threatening vascular disease, including those with impaired kidney function.

Myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA)-positive vasculitis frequently affects the kidney and the lung, with alveolar hemorrhage being fatal. Whereas aggressive immunosuppressive therapies are conventionally used, recent studies have shown the beneficial effect of avacopan, a C5a antagonist, as an alternative to glucocorticoids for ANCA-associated vasculitis (AAV). In patients with pulmonary hemorrhage and severe respiratory failure, however, neither the efficacy of avacopan nor the contribution of this drug to early withdrawal of glucocorticoids is fully qualified. Here, we report a case of AAV presenting with alveolar hemorrhage requiring aggressive ventilatory support in which we experienced the favorable effect of early use of avacopan. A 31-year-old man was referred to our hospital because of a two-week history of blood sputum and positive MPO-ANCA. His respiratory failure deteriorated rapidly, necessitating both mechanical ventilation and extracorporeal membrane oxygenation. A combination therapy with glucocorticoids and rituximab was initiated and avacopan was started on hospital day 8, which resulted in successful remission within six months of admission (Birmingham Vasculitis Activity Score version 3 = 0), and the beneficial effect was sustained for at least 6 months following the discontinuation of glucocorticoid withdrawal (day 156). Thus, avacopan, in combination with immunosuppressives, may not only help suppress the disease activity of AAV but also facilitate early withdrawal of glucocorticoids even in case of life-threatening respiratory failure.