Autosomal dominant ApoA4 mutations present as tubulointerstitial kidney disease with medullary amyloidosis.

Sporadic cases of apolipoprotein A-IV medullary amyloidosis have been reported. Here we describe five families found to have autosomal dominant medullary amyloidosis due to two different pathogenic APOA4 variants. A large family with autosomal dominant chronic kidney disease (CKD) and bland urinary sediment underwent whole genome sequencing with identification of a chr11:116692578 G>C (hg19) variant encoding the missense mutation p.L66V of the ApoA4 protein. We identified two other distantly related families from our registry with the same variant and two other distantly related families with a chr11:116693454 C>T (hg19) variant encoding the missense mutation p.D33N. Both mutations are unique to affected families, evolutionarily conserved and predicted to expand the amyloidogenic hotspot in the ApoA4 structure. Clinically affected individuals suffered from CKD with a bland urinary sediment and a mean age for kidney failure of 64.5 years. Genotyping identified 48 genetically affected individuals; 44 individuals had an estimated glomerular filtration rate (eGFR) under 60 ml/min/1.73 m2, including all 25 individuals with kidney failure. Significantly, 11 of 14 genetically unaffected individuals had an eGFR over 60 ml/min/1.73 m2. Fifteen genetically affected individuals presented with higher plasma ApoA4 concentrations. Kidney pathologic specimens from four individuals revealed amyloid deposits limited to the medulla, with the mutated ApoA4 identified by mass-spectrometry as the predominant amyloid constituent in all three available biopsies. Thus, ApoA4 mutations can cause autosomal dominant medullary amyloidosis, with marked amyloid deposition limited to the kidney medulla and presenting with autosomal dominant CKD with a bland urinary sediment. Diagnosis relies on a careful family history, APOA4 sequencing and pathologic studies.

Autosomal dominant chronic tubulointerstitial nephropathy: do not forget amyloidosis.

Amyloidosis is a rare cause of inherited kidney disease, with most variants responsible for prominent glomerular involvement. In this issue, Kmochová et al. reported the first description of autosomal dominant medullary amyloidosis due to apolipoprotein A4 variants, resulting in slowly progressive chronic kidney disease with minimal proteinuria. Combining next-generation sequencing with histopathological studies incorporating Congo red staining and mass spectrometry should be considered in the diagnostic workup of hereditary tubulointerstitial disorders not identified after routine genetic testing.

ANCA-associated kidney disease preceded by orbital pseudotumor.

INTRODUCTION: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and IgG4-related disease (IgG4-RD) are distinct immune disorders with overlapping clinical and laboratory features. While ANCA positivity excludes IgG4-RD in the 2019 ACR/EULAR classification, this criterion is not uniformly applied, and AAV can form inflammatory masses in various organs and show increase in IgG4 + plasma cells, similar to IgG4-RD. CASE DIAGNOSIS/TREATMENT: A 5-year-old female with history of orbital mass diagnosed as IgG4-RD presents with acute kidney injury. She has a myeloperoxidase ANCA, and kidney biopsy shows pauci-immune crescentic glomerulonephritis and acute tubulointerstitial nephritis with increased IgG4 + plasma cells and tubular basement membrane (TBM) deposits. CONCLUSION: In isolation, TBM deposits and increased IgG4 + plasma cells are suggestive of IgG4-RD. In the context of a positive ANCA and pauci-immune crescentic glomerulonephritis, however, increased IgG4 + plasma cells due to AAV are favored. In cases with features of IgG4-RD, ANCA positivity suggests an alternate diagnosis of AAV to be more likely.

IgG4-related kidney disease: Clinicopathologic features, differential diagnosis, and mimics.

IgG4-related kidney disease (IgG4-RKD) encompasses all forms of kidney disease that are part of IgG4-related disease (IgG4-RD). First recognized as IgG4-related tubulointerstitial nephritis (IgG4-TIN), and then IgG4-related membranous glomerulonephritis (IgG4-MGN), we now recognize additional patterns of interstitial nephritis, glomerular disease, and vascular disease that can be seen as part of IgG4-RKD. The clinical presentation is variable and can include acute or chronic kidney injury, proteinuria or nephrotic syndrome, mass lesion(s), and obstruction. While usually associated with other organ involvement by IgG4-RD, kidney-alone involvement is present in approximately 20 % of IgG4-RKD. Compared to IgG4-RD overall, patients with IgG4-RKD are more likely to show increased serum IgG4 or IgG, and more likely to have hypocomplementemia. In this review, we extensively cover other types of autoimmune and plasma cell-rich interstitial nephritis, mass forming inflammatory diseases of the kidney, and other mimics of IgG4-TIN, in particular ANCA-associated disease.

PLA2R-positive membranous nephropathy in IgG4-related disease.

BACKGROUND: IgG4-related disease (IgG4-RD) is a fibroinflammatory disease that affects multiple organs, including the pancreas, lacrimal glands, salivary glands, periaortic/retroperitoneum, and kidney. Interstitial nephritis is a typical renal disorder associated with IgG4-RD, but membranous nephropathy is also seen in some cases. CASE PRESENTATION: Herein we report on the case of a 77-year-old male patient with nephrotic syndrome and IgG4-related lung disease. His serum phospholipase A2 receptor (PLA2R) antibody was positive. His renal biopsy specimen was also positive for PLA2R. The renal biopsy specimen showed membranous nephropathy with equal IgG3 and IgG4 immunofluorescence staining and no interstitial nephritis, suggesting IgG4-RD manifesting as membranous nephropathy. CONCLUSIONS: Nephrotic syndrome caused by membranous nephropathy is sometimes associated with IgG4-RD. In such cases, even if serum PLA2R antibody is positive, it should be considered that the membranous nephropathy may be secondary to IgG4-RD.

Nephrotic syndrome with acute kidney injury due to combination therapy of immune checkpoint inhibitors: a case report and review of the literature.

BACKGROUND: Recent studies have focused on immune checkpoint inhibitors. Renal complications associated with the use of immune checkpoint inhibitors are uncommon compared with other immune-related adverse events. Acute interstitial nephritis accounts for most of these renal complications, with nephrotic syndrome quite rare. We herein report a case of nephrotic syndrome associated with immune checkpoint inhibitors that was more severe than that in previous cases. By comparing this case with previous reports, the possible reasons for the particular severity of this case are discussed. CASE PRESENTATION: A 75-year-old man developed nephrotic syndrome with acute kidney injury after the first combination therapy of nivolumab and ipilimumab for malignant pleural mesothelioma. The results of a kidney biopsy indicated minimal change disease with mild atherosclerosis, acute interstitial nephritis, and fusion of nearly all podocyte foot processes. Nivolumab and ipilimumab therapy were stopped, and treatment with corticosteroids was initiated. We investigated previously reported cases of nephrotic syndrome using immune checkpoint inhibitors. Seventeen cases of immune checkpoint inhibitor-related nephrotic syndrome, including ours, have been reported. Two of the 17 patients with immune checkpoint inhibitor-related nephrotic syndrome required hemodialysis treatment for acute kidney injury. Unlike many previously reported cases, the present patient was administered two different immune checkpoint inhibitors, which may be one of the reasons for the development of severe nephrotic syndrome. CONCLUSIONS: In addition to previously reported risk factors, immune checkpoint inhibitor combination therapy can exacerbate nephrotic syndrome compared to immune checkpoint inhibitor monotherapy.

BK DNAemia and native kidney polyomavirus nephropathy following lung transplantation.

BK virus DNAemia (BKPyV) and nephropathy are common after kidney transplant; however, there are limited data on BK infections in nonrenal solid organ transplant recipients. We examined the frequency, clinical and pathologic features, and kidney and lung outcomes of BKPyV and BK virus native kidney nephropathy (BKVN) in lung transplant recipients at our center. Among 878 recipients transplanted from 2003 to 2019, 56 (6%) developed BKPyV at a median of 30.1 months after transplant (range, 0.6-213) and 11 (1.3%) developed BKVN at a median of 46 months after transplant (range, 9-213). The incidence of end-stage kidney disease was significantly higher in patients with peak viral load ≥10 000 copies/mL (39% vs 8%, P < .001). All cases of BKVN were in patients with peak viral load of ≥10 000 copies/mL, and 55% of these patients developed end-stage kidney disease. Despite the reduction of immunosuppression to treat BKVN, only 1 patient developed acute rejection, and lung function was stable >1 year. BKPyV and nephropathy are more common after lung transplantation than previously reported. Routine screening for BKPyV should be considered in all lung transplant recipients.

A case of IgG4-related interstitial nephritis with ureteral obstruction: case report and literature review.

BACKGROUND: IgG4-related disease (IgG4-RD) is a newly discovered systemic disease that can affect any organ or tissue in the body. IgG4-related kidney disease (IgG4-RKD) is relatively rare but essential to IgG4-RD. However, there are few reports of IgG4-RD mimicking malignant ureteral tumors leading to hydronephrosis. We report here a rare case of IgG4-RD involving the ureter. CASE PRESENTATION: An 87-year-old man presented to our nephrology department with anorexia, nausea, and acute kidney injury in November 2020. Urinary computed tomography (CT) examination revealed a right lower ureter mass with right renal and ureter hydronephrosis. The serum level of IgG4 was 1890 mg/dL, and the concurrently renal biopsy revealed extensive infiltration of IgG4-positive plasma cells in renal interstitium, which was diagnosed as IgG4-associated tubule-interstitial nephritis(IgG4-TIN). The renal function improved significantly after double-J tube implantation of the right ureter and moderate-dose hormone therapy. The serum IgG4 decreased to the normal range, and the right lower ureter mass almost disappeared after one year of low-dose hormone maintenance therapy. CONCLUSION: IgG4-RD can present as a mass in the renal pelvis and (or) ureter, leading to hydronephrosis. Therefore, early recognition of this disease is significant. Most patients respond well to hormonal therapy to avoid surgical treatment due to misdiagnosis as malignant tumors, causing secondary harm to patients.

A case of tubulointerstitial nephritis and uveitis syndrome accompanied by subclinical choroiditis.

BACKGROUND: Tubulointerstitial nephritis and uveitis (TINU) syndrome is an uveits characterized by complications of idiopathic acute tubulointerstitial nephritis, and most cases present only anterior uveitis. We report a case of TINU syndrome in which the presence of choroiditis was revealed by multimodal imaging. CASE PRESENTATION: A 12-year-old male visited our hospital with a 6-day history of ocular pain and hyperemia. Conjunctival and ciliary injections, 1 + flare and 3 + cells of anterior chamber inflammation with mutton fat keratic precipitates were observed in both eyes (OU), together with redness and swelling of the optic disc OU. Laboratory tests showed slightly high levels of soluble IL-2R and serum ß2 microglobulin and markedly high levels of urinary ß2 microglobulin. The diagnosis of probable TINU syndrome was established on the basis of bilateral uveitis and urinalysis results in accordance with a clinical criteria of tubulointerstitial nephritis. With treatment with oral prednisolone (PSL) at 20 mg/day, ocular findings improved, and the dose of PSL was gradually reduced and withdrawn 6 months later. However, 1 month later from the withdrawal, ocular inflammation recurred with the presence of retinal exudates and snowball vitreous opacities in the peripheral retina OU. Fluorescein angiography showed leakages from peripheral retinal vessels and staining corresponding to retinal exudates. Indocyanine green angiography showed hypofluorescent dots scattered over the ocular fundus. Optical coherence tomography revealed the presence of choroidal thickening. Laser speckle flowgraphy color map showed a relatively cooler color. Findings from these multimodal images indicated the presence of subclinical choroiditis; therefore, oral PSL was administered again, and ocular inflammatory findings were improved. CONCLUSIONS: TINU syndrome can exhibit subclinical choroiditis detected with multimodal imaging. Further studies are necessary to determine the frequency of subclinical choroiditis in TINU syndrome.

Karyomegalic interstitial nephritis as a rare cause of kidney graft dysfunction: case report and review of literature.

Karyomegalic interstitial nephritis (KIN) is a rare cause of chronic interstitial nephritis characterized by enlarged renal tubular epithelial nuclei. The first case of KIN reported in a kidney graft was in 2019. Here, we report the first case of KIN in 2 brothers receiving kidneys from 2 different unrelated living donors. A male kidney transplant recipient with focal segmental glomerulosclerosis as the original kidney disease presented with graft impairment and proteinuria, and graft biopsy revealed KIN. This patient had a brother who was also a kidney transplant recipient and had one episode of graft impairment and was diagnosed with KIN as well.

A report of three cases of patients with tubulointerstitial nephritis with IgM-positive plasma cells, treatment, and serum-IgM as a sensitive marker for relapse.

BACKGROUND: Tubulointerstitial nephritis with IgM-positive plasma cells (IgMPC-TIN) is a newer disease about which there are many unclear points. Glucocorticoid therapy is effective in many cases of IgMPC-TIN; however, relapse during glucocorticoid tapering has been reported. Relapse and its treatment are poorly defined. CASE PRESENTATION: Case 1 was a 61-year-old man with renal dysfunction and proteinuria. Tubulointerstitial nephritis and IgM-positive plasma cells were observed in a renal biopsy. He was diagnosed with IgMPC-TIN accompanied by Fanconi syndrome and distal renal tubular acidosis (d-RTA). Prednisolone (PSL; 30 mg daily, 0.45 mg/kg/day) treatment was highly effective, and PSL was gradually tapered and discontinued after 1 year. However, 1 month after PSL discontinuation, therapeutic markers were elevated. Therefore, PSL (10 mg daily, 0.15 mg/kg/day) was administered, and the markers indicated improvement. Case 2 was a 43-year-old woman referred for renal dysfunction and proteinuria. Laboratory data revealed that she had primary biliary cholangitis (PBC), d-RTA, and Fanconi syndrome. A renal biopsy showed accumulation of IgM-positive plasma cells in the tubulointerstitium without any glomerular changes. A diagnosis of IgMPC-TIN was made and the patient was started on PSL (35 mg daily, 0.6 mg/kg/day). Therapeutic markers decreased immediately and PSL was discontinued after 1 year. Three months later, the proteinuria and Fanconi syndrome worsened. PSL treatment was restarted (20 mg daily, 0.35 mg/kg/day) and markers indicated improvement. Case 3 was a 45-year-old woman with renal dysfunction and proteinuria. Tubulointerstitial nephritis and IgM-positive plasma cells were observed in a renal biopsy. The patient had PBC, Sjögren syndrome, d-RTA, and Fanconi syndrome, and the diagnosis of IgMPC-TIN was made. The patient was started on PSL (30 mg daily, 0.4 mg/kg/day) and disease markers decreased immediately. However, when PSL was tapered to 15 mg daily (0.2 mg/kg/day), the patient's serum IgM levels increased; therefore, we maintained the PSL at 15 mg daily (0.2 mg/kg/day). CONCLUSION: We report three cases of relapsed IgMPC-TIN associated with reduction or discontinuation of glucocorticoid therapy. In these cases, elevation of serum IgM preceded that of other markers such as urinary ß2-microglobulin, proteinuria, and glycosuria. We recommend monitoring serum IgM levels while tapering glucocorticoids; a maintenance dose of glucocorticoid should be considered if relapse is suspected or anticipated.

Renal tubular acidosis without interstitial nephritis in Sjögren's syndrome: a case report and review of the literature.

BACKGROUND: Renal tubular acidosis is the principal clinical feature associated with tubulointerstitial nephritis in patients with primary Sjögren's syndrome. Renal tubular dysfunction due to interstitial nephritis has been considered the underlying pathophysiology connecting renal tubular acidosis and primary Sjögren's syndrome. However, the detailed mechanisms underlying the pathophysiology of renal tubular acidosis in primary Sjögren's syndrome is not fully understood. CASE PRESENTATION: A 30-year-old woman was admitted with complaints of weakness in the extremities. The patient was hospitalized thirteen years earlier for similar issues and was diagnosed with hypokalemic paralysis due to distal renal tubular acidosis with primary Sjögren's syndrome. This diagnosis was based on a positive Schirmer's test. Besides, anti-Sjögren's syndrome-related antigen A was also detected. Laboratory tests indicated distal RTA; however, a renal biopsy showed no obvious interstitial nephritis. Laboratory tests conducted during the second admission indicated distal renal tubular acidosis. Therefore, a renal biopsy was performed again, which revealed interstitial nephritis. Histological analysis of acid-base transporters revealed the absence of vacuolar type H+-ATPases in the collecting duct. The vacuolar type H+-ATPase was also absent in the past renal biopsy, suggesting that the alteration in acid-base transporters is independent of interstitial nephritis. CONCLUSIONS: This case study demonstrates that vacuolar-type H+-ATPases are associated with distal renal tubular acidosis, and distal renal tubular acidosis precedes interstitial nephritis in patients with primary Sjögren's syndrome.

Systemic sarcoidosis presenting as a rare combination of interstitial nephritis with necrotizing vasculitis and urinary retention due to prostate involvement: a case report.

BACKGROUND: Sarcoidosis affects multiple organs and exhibits diverse clinical manifestations. Although tubulointerstitial nephritis is a known feature of renal involvement, necrotizing vasculitis is rare. Furthermore, prostate involvement with urinary retention is unusual in patients with sarcoidosis. Here, we report a case of systemic sarcoidosis with a rare combination of manifestations and different acute kidney injuries. CASE PRESENTATION: A 66-year-old man developed sudden urinary retention and fever. He was diagnosed with prostatitis and admitted to our hospital. An indwelling urethral catheter was inserted, and antimicrobial therapy was initiated; however, the prostatitis was refractory. Computed tomography revealed enlarged mediastinal lymph nodes. Analysis of transbronchoscopic lymph node and prostate biopsies showed epithelioid cell granulomas, suggesting systemic sarcoidosis. During the clinical course, the serum creatinine level rapidly increased to 2.36 mg/dL without oliguria. A kidney biopsy revealed tubulointerstitial injury with moderate lymphohistiocytic infiltration and small-vessel vasculitis in the interstitium. Following oral administration of 60 mg/day prednisolone, the patient's renal function immediately improved, and urinary retention did not recur. CONCLUSIONS: To the best of our knowledge, this is the first reported case of sarcoidosis with two unusual complications. Given its clinical course and pathology, this case is clinically valuable.

Biopsy-proven first dose of oxaliplatin-induced acute tubular necrosis leading to end-stage renal failure: a case report.

BACKGROUND: Oxaliplatin is an anticancer therapy for pancreatic, gastric, and colorectal cancers. It is also used in patients with carcinomas of unknown primary sites. Oxaliplatin is associated with less frequent renal dysfunction than other conventional platinum-based drugs such as cisplatin. Albeit, there have been several reports of acute kidney injury with frequent use. In all cases, renal dysfunction was temporary and did not require maintenance dialysis. There have been no previous reports of irreversible renal dysfunction after a single dose of oxaliplatin. CASE PRESENTATION: Previous reports of oxaliplatin-induced renal injury occurred after patients received multiples doses. In this study, a 75-year-old male with unknown primary cancer and underlying chronic kidney disease developed acute renal failure after receiving the first dose of oxaliplatin. Suspected of having drug-induced renal failure through an immunological mechanism, the patient was treated with steroids; however, treatment was ineffective. Renal biopsy ruled out interstitial nephritis and revealed acute tubular necrosis. Renal failure was irreversible, and the patient subsequently required maintenance hemodialysis. CONCLUSIONS: We provide the first report of pathology-confirmed acute tubular necrosis after the first dose of oxaliplatin which led to irreversible renal dysfunction and maintenance dialysis.

An unusual form of kidney injury without glomerulonephritis in microscopic polyangiitis: a case report.

BACKGROUND: Microscopic polyangiitis (MPA), a kind of antineutrophil cytoplasmic autoantibody associated vasculitis (AAV), predominantly affects small-sized vessels. MPA is a significant cause of the pulmonary-renal syndrome. Pauci-immune necrotizing and crescentic glomerulonephritis is the typical renal histological feature of AAV. Tubulointerstitial lesions may occur and mostly form with inflammatory cell infiltration in the interstitium. However, a few cases reported only tubulointerstitial involvement without glomerular lesions in patients with MPA. CASE PRESENTATION: We present an MPA case, a 70-year-old male patient diagnosed with acute kidney injury accompanying the dialysis requirement. Only acute tubulointerstitial nephritis was revealed in kidney biopsy without evidence of glomerular injury. Also, interstitial pulmonary fibrosis was determined on computerized tomography, and myeloperoxidase antineutrophil cytoplasmic autoantibody was positive. Consequently, we have considered the main diagnosis as MPA. We did not prefer a standard tubulointerstitial nephritis treatment regimen due to the presence of life-threatening systemic vasculitis. Treatment was established like crescentic glomerulonephritis. Induction therapy consisted of pulse steroid, cyclophosphamide, and plasmapheresis. Unfortunately, severe SARS-CoV-2 infection caused death during induction therapy in this case. CONCLUSIONS: The lack of glomerular injury and solely interstitial inflammation is atypical regarding AAV involvement in the kidney. This diversity might be initially considered as only a simple histological elaboration. However, it is a significant entity for guiding the treatment of AAV.

Kidney Effects by Alternative Classes of Medicines in Patients and Relationship to Effects in Nonclinical Toxicity Studies.

Drug-induced kidney injury has historically been associated with renal tubule injury related to small molecule pharmaceuticals such as nonsteroidal anti-inflammatory drugs, antineoplastic agents, or antibiotics, but as a greater number of alternative classes of medicines such as biotherapeutics, molecular-targeted antineoplastic drugs, chimeric antigen receptor T-cell therapies, antibody-drug conjugates, oligonucleotide therapies, or other immunomodulatory drugs come to market, the presentation of drug-induced nephrotoxicity is changing. This review article describes the potential rare clinical events in drug-induced kidney injury that might be noted with these new therapies and their potential impact on patients. Potential pathogenic mechanisms related to immunogenicity, immune complex formation, and stimulation of downstream proinflammatory pathways with some of these alternative medicine classes have resulted in the potential for glomerulonephritis, acute interstitial nephritis, renal vasculitis, and other immune-mediated renal disorders in humans. This contrasts with nonclinical toxicity studies, where biologic therapies more often result in vasculitis and glomerulonephritis associated with antidrug antibodies and immunomodulatory pharmacology, and which are not always predictive of clinical effects. While nonclinical antidrug antibody-related renal disease is generally not clinically relevant, other immune-mediated nephrotoxicities associated with immunomodulatory drugs may be predictive of clinical adverse events. Fortunately, these conditions are still rare and account for a small percentage of serious adverse events in kidneys of patients.

Clinical management of a granulomatous tubulointerstitial nephritis associated with a bilateral granulomatous anterior uveitis: A challenging case report and review of the literature.

Acute granulomatous tubulointerstitial nephritis (GTIN) is a rare finding in renal biopsy. Differential diagnosis is facilitated when GTIN is associated with granulomatous bilateral anterior uveitis (GBAU). Nevertheless, differentiation between a rare form of granulomatous tubulointerstitial nephritis and uveitis syndrome (TINU) and sarcoidosis can be challenging. We report a case of biopsy-proven GTIN with concomitant GBAU, leading to a dead-end diagnosis. We discuss workup and propose a diagnostic algorithm based on a literature review. We also report a successful treatment of ophthalmologic and renal relapse using mycophenolate mofetil.

Simultaneous subacute interstitial nephritis and anticoagulant-related nephropathy related to novel oral anticoagulants use.

Introduction: Interstitial nephritis related to novel oral anticoagulants was only reported in sporadic case reports and none was accompanied by anticoagulants related nephropathy (ARN).Case Report: We presented here a case of biopsy-proven subacute interstitial nephritis (SubAIN) accompanied by ARN after oral dabigatran to alarm clinicians. This case manifested with gross hematuria, acute kidney injury, slightly prolonged thrombin time, moderate anemia, moderate proteinuria, a large quantity of intratubular hemoglobin casts confirmed by hemoglobin antibody immunohistochemical staining which presumed to occur around 1 week after dabigatran and subacute interstitial nephritis accompanied by focal proliferative glomerulonephritis. Serum creatinine level did not continue to elevate after discontinuation of the oral anticoagulant. With the subsequent supportive therapy, it decreased to some extent then reduced to normal with the help of prednisone (half of the full dose).Conclusions: When we came across a patient who manifested as hematuria or acute kidney injury with a history of anticoagulants usage, we should think of ARN and pay more attention on history collection. Secondly, subacute interstitial nephritis may coexist with ARN. Thirdly, hemoglobin immunohistochemical staining may be helpful to make it clear whether the intra-tubular protein casts came from red blood cells. In addition, for those patients who may have decreased kidney function, anticoagulants dose should be reduced to prevent the occurrence of ARN.

Acute tubulointerstitial nephritis in a patient with early bronchial tuberculosis.

Patients with chronic kidney disease (CKD) are commonly at high risk of tuberculosis (TB). Conversely, TB rarely causes tubulointerstitial nephritis. A 75-year-old Japanese man who was undergoing periodic follow-ups for CKD stage G3aA3 with membranous nephropathy was diagnosed with acute kidney injury (AKI) (estimated glomerular filtration rate [eGFR]: 15 mL/min/1.73 m2) without prerenal AKI. He reported developing recent-onset cough 3 weeks prior to presenting to us. Renal biopsy revealed acute tubulointerstitial nephritis along with known membranous nephropathy. CD4+ helper T cells comprised most lymphocytes in the tubulointerstitium. Results of the interferon-gamma release assay, sputum smear test, polymerase chain reaction (PCR), and culture test were positive for TB. Chest computed tomography revealed thickening of the left bronchial wall; therefore, a diagnosis of early bronchial TB was made; his urine culture and PCR were negative for TB. At four months after TB treatment with no immunosuppressive therapy, his eGFR improved to 50 mL/min/1.73 m2, and based on this progress, the AKI was diagnosed as tuberculosis-associated tubulointerstitial nephritis (TATIN). Although TATIN typically occurs with chronic or miliary tuberculosis, it is very rare in early bronchial TB. Identification of TATIN is important in kidney diseases of unknown etiology, and treatment with anti-TB drugs is necessary.

Juxtapapillary Choroidal Neovascularization in a Young Woman with Tubulointerstitial Nephritis and Uveitis (TINU) Syndrome with Onset in Pediatric Age.

We describe the unusual case of a young woman with tubulointerstitial nephritis and uveitis (TINU) with bilateral diffuse uveitis and optic nerve inflammatory involvement since she was a child in the 1990s. Imaging diagnostic tools such as fluorescein angiography, indocyanine green angiography, optical coherence tomography (OCT), and OCT angiography revealed inactive juxtapapillary choroidal neovascularization (CNV) after 25 years of follow-up. After treatment, uveitis went into remission with BCVA 20/20 in both eyes and CNV lesions became inactive. Although anterior uveitis is more frequently reported in TINU, posterior uveitis with inflammatory involvement of the optic nerve should be accurately investigated to rule out juxtapapillary CNV, both at the time of active uveitis and during follow-up, since TINU may be complicated by CNV even at the later stages of the inflammatory process.