ALK-Rearranged Epithelioid Mesenchymal Neoplasm: Expanding the Spectrum of Tyrosine Kinase-Altered Mesenchymal Tumors.

The anaplastic lymphoma kinase (ALK) gene encodes a receptor tyrosine kinase, and fusions involving this gene have been reported in a variety of mesenchymal neoplasms. ALK-altered tumors with epithelioid morphology have been described in epithelioid inflammatory myofibroblastic sarcoma and epithelioid fibrous histiocytoma. Herein, we describe the clinicopathologic features of 7 ALK-rearranged mesenchymal tumors with epithelioid morphology occurring predominately in the pediatric population. Tumors occurred in 4 females and 3 males with an age ranging from 1 month to 28 years. Five tumors were superficial and solitary, while 1 presented with multiple peritoneal/omental nodules, and 1 presented as a large mediastinal mass. Morphologically, all tumors comprised epithelioid cells arranged in sheets, anastomosing cords, or small clusters embedded in a myxohyaline stroma. The cells had slightly variably sized ovoid nuclei with moderately prominent nucleoli and abundant eosinophilic cytoplasm. Four cases had sparse mitotic figures without necrosis. The remaining 3 tumors (2 deep and 1 superficial) had more than 10 mitoses per 10 high-power fields as well as foci of necrosis. ALK fusions were identified in all cases. The fusion partners included HMBOX1 (n = 1), VCL (n = 1), PRRC2B (n = 1), MYH10 (n = 1), STRN (n = 1), and EML4 (n = 2). One tumor recurred locally 2 years after initial resection; 1 patient had widely metastatic disease (mediastinal tumor). At the time of last follow-up (n = 6), 4 patients were alive without evidence of disease, 1 died due to complications of therapy (peritoneal tumor), and 1 was alive with disease. Our findings expand the spectrum of ALK-rearranged mesenchymal tumors. Our cases predominately occurred in older children and mainly exhibited epithelioid to round cell morphology, as opposed to spindle cell morphology. We also show that tumors in a deep location with higher-grade features follow a more aggressive clinical course.

Acute Interstitial Nephritis in the Pediatric Population: A Review of Etiologic Associations, Histologic Findings, and Clinical Outcome.

BACKGROUND: Acute interstitial nephritis (AIN) is an infrequent cause of acute kidney injury in the pediatric population with a broad range of etiologies. This retrospective review attempts to characterize AIN in the pediatric population, delineate etiologic factors, histologic features, and clinical outcome. MATERIALS AND METHODS: Institutional pathology reports were queried for a diagnosis of AIN between 1/2010 and 10/2021. Archived slides and reports and clinical records were reviewed. RESULTS: Twenty-four patients were identified whose ages ranged from 5 to 20 years. A 8 cases (37.5%) were characterized as tubulointerstitial nephritis and uveitis (TINU), 4 cases (16.7%) were associated with an autoimmune disease, 4 cases (16.7%) were likely drug induced, and 8 cases (37.5%) had unclear etiology. DISCUSSION: Although all cases of drug induced interstitial nephritis contained eosinophils they were not exclusive to drug induced interstitial nephritis. A prominent plasma cell infiltrate was seen in both cases of Sjögren's associated interstitial nephritis. The vast majority (n = 18, 75%) showed an improved serum creatinine (<1 mg/dL) 1 year post diagnosis/at last follow-up. In this pediatric series of AIN, TINU contributed to a large subset of cases with known etiologies. On follow up, majority of the cases demonstrated recovery of renal function.

Clinical Significance of Renal Allograft Urothelial Thickening Identified by Ultrasound.

OBJECTIVES: To assess the etiology and clinical implications of ultrasound (US)-diagnosed urothelial thickening (UT) in renal transplants. METHODS: Patients with renal transplants who had UT diagnosed by US from January 2000 to December 2018 were retrospectively identified and compared to patients with transplants without UT scanned during the study period. Medical records were reviewed for demographics, US findings, pathologic results, laboratory values, and clinical outcomes and compared between groups by Fisher exact and t tests. RESULTS: A total of 143 patients with UT and 128 controls comprised our cohorts. The patient age in the UT group versus controls (mean ± SD, 50.2 ± 16.5 versus 51.2 ± 15.3 years) and the time since transplant (2.9 ± 4.2 versus 2.4 ± 5.8 years) were similar. Patients with UT were more likely to be female than controls (76 of 143 [53.1%] versus 53 of 128 [41.4%]; P = .07), but the difference was not statistically significant, and patients with UT were more likely to have indwelling stents (31 of 143 [21.7%] versus 9 of 128 [7.0%]; P = .001) and hydronephrosis (25 of 143 [17.4%] versus 11 of 128 [8.6%]; P = .03). At biopsy, rejection and vascular sclerosis were more likely in patients with UT compared to controls (24 of 25 [49.0%] versus 11 of 43 [25.6%]; P = .031; 42 of 49 [85.7%] versus 22 of 43 [51.2%]; P = .0005, respectively), whereas acute tubular necrosis was similar. The sensitivity (50.0%) and specificity (74.4%) of UT for rejection were low. CONCLUSIONS: Urothelial thickening correlates with US findings of urinary obstruction and indwelling stents, suggesting a possible mechanical component to UT's etiology. Although transplant rejection and vascular sclerosis were more frequent at biopsy in the UT group than controls, UT had low sensitivity and specificity for rejection.

Trabectedin Enhances Oncolytic Virotherapy by Reducing Barriers to Virus Spread and Cytotoxic Immunity in Preclinical Pediatric Bone Sarcoma.

We previously reported that the DNA alkylator and transcriptional-blocking chemotherapeutic agent trabectedin enhances oncolytic herpes simplex viroimmunotherapy in human sarcoma xenograft models, though the mechanism remained to be elucidated. Here we report trabectedin disrupts the intrinsic cellular anti-viral response which increases viral transcript spread throughout the human tumor cells. We also extended our synergy findings to syngeneic murine sarcoma models, which are poorly susceptible to virus infection. In the absence of robust virus replication, we found trabectedin enhanced viroimmunotherapy efficacy by reducing immunosuppressive macrophages and stimulating granzyme expression in infiltrating T and NK cells to cause immune-mediated tumor regressions. Thus, trabectedin enhances both the direct virus-mediated killing of tumor cells and the viral-induced activation of cytotoxic effector lymphocytes to cause tumor regressions across models. Our data provide a strong rationale for clinical translation as both mechanisms should be simultaneously active in human patients.

Correlation of Red Blood Cell Casts With Renal Dysfunction in Patients With Infection-related Glomerulonephritis.

CONTEXT.­: Infection-related glomerulonephritis (IRGN) usually manifests as a proliferative immune-complex glomerulonephritis. The degree of renal dysfunction at presentation can vary. Association with histologic features on kidney biopsy remains unknown. OBJECTIVE.­: To study the correlation between renal function in IRGN at the time of biopsy and the severity of histologic features. DESIGN.­: Culture-proven IRGN cases at our facility were included and divided based on estimated glomerular filtration rate (eGFR) 15 ml/min/1.73 m2. Patients' demographic and pathologic findings were obtained from electronic medical records and kidney biopsy reports. RESULTS.­: In total, 104 cases were diagnosed with IRGN on biopsy (mean age, 55.6 ± 15.6 years; male, n = 79 [76%]; median eGFR, 14.5 mL/min/1.73 m2), and 51 of 104 showed eGFR <15 mL/min/1.73 m2. Among all the histologic features assessed, only percent tubules with red blood cell (RBC) casts showed statistical difference, being significantly higher in the lower eGFR group (P = .004). Multivariable logistic regression analysis also showed that %tubules with RBC casts were associated with lower eGFR (odds ratio, 1.12; 95% CI, 1.01-1.24; P = .01). Patients with 5% or more RBC casts (n = 31) showed a lower eGFR (P = .02) and a higher %cellular crescent (P < .001) compared with those with less than 5% RBC casts. Patients with concomitant anticoagulant therapy (n = 11) showed higher percentages of RBC casts than those without anticoagulants (P = .02). CONCLUSIONS.­: Particular attention to the extent of RBC casts on kidney biopsy is recommended in patients with IRGN because these portend worse renal dysfunction, more so in patients requiring anticoagulation (including for hemodialysis) because they are especially vulnerable to developing anticoagulant-related nephropathy.

Research Letter: Is the 129S1/SvImJ Mouse Strain More Suitable to Study Anticoagulant-Related Nephropathy Than the C57BL/6 Strain?

Background: We have previously demonstrated that excessive anticoagulation with warfarin or dabigatran may result in acute kidney injury with red blood cell (RBC) tubular casts in some patients with chronic kidney disease, and this condition was named anticoagulant-related nephropathy (ARN). 5/6 nephrectomy (5/6NE) rats treated with warfarin or dabigatran reproduce the main pathologic features of human ARN. We had reported that 5/6NE C57BL/6 mice only partially develop ARN with increased serum creatinine and hematuria but no RBC tubular casts in the kidney. Objectives: The aim of this study was to investigate whether ARN can develop in 5/6NE 129S1/SvImJ mice. Methods: 5/6NE was performed in 129S1/SvImJ mice. Three weeks after 5/6NE, mice were treated with warfarin (1.0 and 1.5 mg/kg/day) or vehicle for 7 days. Serum creatinine, hematuria, and prothrombin time (PT) were monitored daily. Renal morphology was evaluated at the end of the studies. Results: Treatment with warfarin resulted in PT elevation 2 to 3 folds from baseline (1.0 mg/kg/day warfarin) and 4 to 5 folds from baseline (1.5 mg/kg/day warfarin) by day 7. Serum creatinine and hematuria elevated by day 7 in a dose-dependent manner. Histologically, 2 of 8 (25%) 5/6NE mice had RBCs in the tubules, and there was acute tubular epithelial cell injury in all warfarin-treated 5/6NE 129S1/SvImJ mice. Conclusions: Our findings suggest that 129S1/SvImJ mouse strain is a more suitable murine model to study ARN than C57BL/6 mouse strain.

Contexte: Nous avons précédemment démontré qu'un traitement anticoagulant excessif par warfarine ou dabigatran pouvait entraîner une insuffisance rénale aiguë avec formation de cylindres urinaires avec globules rouges (GR) chez certains patients atteints d'insuffisance rénale chronique. Cette affection a été nommée « néphropathie liée à un anticoagulant ¼ (NLA). Les rats 5/6NE (néphrectomie 5/6) traités par warfarine ou dabigatran reproduisent les principales caractéristiques pathologiques d'une NLA chez l'humain. Nous avions rapporté que les souris 5/6NE C57BL/6 ne développaient qu'une NLA partielle, présentant une augmentation de la créatinine sérique et de l'hématurie, mais aucune formation de cylindres urinaires avec GR dans les reins. Objectif: Vérifier si une NLA peut se développer chez les souris 5/6 NE 129S1/SvImJ. Méthodologie: Une 5/6NE a été réalisée chez des souris 129S1/SvImJ. Trois semaines après l'intervention, les souris ont été traitées avec de la warfarine (1,0 mg/kg/jour et 1,5 mg/kg/jour) ou un placebo pendant 7 jours. La créatinine sérique, l'hématurie et le temps de prothrombine (TP) ont été surveillés quotidiennement. La morphologie rénale a été évaluée à la fin des études. Résultats: Au jour 7, le traitement par warfarine avait entraîné une augmentation du TP de 2 à 3 fois par rapport à la mesure initiale pour le groupe traité avec 1,0 mg/kg/jour, et de 4 à 5 fois pour le groupe traité avec 1,5 mg/kg/jour. Les taux de créatinine sérique et l'hématurie s'étaient élevés en fonction de la dose. Sur le plan histologique, 2 souris 5/6NE sur 8 (25 %) avaient des globules rouges dans les tubules, et toutes les souris 5/6NE 129S1/SvImJ traitées avec la warfarine présentaient une atteinte aiguë des cellules tubulaires épithéliales. Conclusion: Nos résultats suggèrent que la souche de souris 129S1/SvImJ serait un modèle murin plus approprié que la souche C57BL/6 pour étudier la néphropathie liée à un anticoagulant.

N-acetylcysteine ameliorates hematuria-associated tubulointerstitial injury in 5/6 nephrectomy mice.

Chronic kidney disease (CKD) is characterized by increased interstitial fibrosis and tubular atrophy (IFTA) in the kidney. Chronic hematuria is a hallmark of several human kidney diseases and often is seen in patients on anticoagulation therapy. We had previously demonstrated that chronic hematuria associated with warfarin increases IFTA in 5/6 nephrectomy (5/6NE) rats, and such treatment increases reactive oxygen species (ROS) in the kidney. The goal of this study was to evaluate the effects of the antioxidant N-acetylcysteine (NAC) on the progression of IFTA in 5/6NE mice. 5/6NE C57BL/6 and 5/6NE 129S1/SvImJ mice were treated with warfarin alone or with warfarin and NAC for 23 weeks. Serum creatinine (SCr), hematuria, blood pressure (BP), and ROSs in the kidney were measured; kidney morphology was evaluated. Warfarin doses were titrated to achieve prothrombin time (PT) increase to the levels seen with therapeutic human doses. Warfarin treatment resulted in an increased SCr, systolic BP, hematuria, expression of TGF-ß and ROS in the kidney in both mouse strains. Tumor necrosis factor alpha (TNF-ɑ) levels in the serum were increased in 5/6NE mice treated with warfarin. IFTA was increased as compared with control 5/6NE mice, and this increase in IFTA was more prominent in 129S1/SvImJ than in C57BL/6 mice. NAC ameliorated the warfarin-associated increase in SCr and BP but not hematuria. IFTA, TGF-ß, and ROS in the kidney as well as TNF-ɑ levels in the serum were reduced in mice treated with NAC and warfarin as compared to mice treated with warfarin alone. NAC mitigates the increase in SCr and IFTA in mice with chronic hematuria by reducing oxidative stress in the kidney. This data open novel possibilities for treatments in CKD patients.

Kidney Biopsy Corner: Amyloidosis.

Amyloidosis is an infiltrative disease caused by misfolded proteins depositing in tissues. Amyloid infiltrates the kidney in several patterns. There are, as currently described by the International Society of Amyloidosis, 14 types of amyloid that can involve the kidney, and these types may have different locations or clinical settings. Herein we report a case of AA amyloidosis occurring in a 24-year-old male with a history of intravenous drug abuse and provide a comprehensive review of different types of amyloids involving the kidney.

The Diagnostic Conundrum of Glomerular Crescents With IgA Deposits.

Introduction: Glomerulonephritis (GN) with crescents and IgA deposits in kidney biopsy poses a frequent diagnostic and therapeutic dilemma because of multiple possibilities. Methods: Native kidney biopsies showing glomerular IgA deposition and crescents (excluding lupus nephritis) were identified from our biopsy archives between 2010 and 2021. Detailed clinicopathologic features were assessed. One-year clinical follow-up on a subset of cases was obtained. Results: A total of 285 cases were identified, and these clustered into IgA nephropathy (IgAN, n = 108), Staphylococcus or other infection-associated GN/infection-related GN (SAGN/IRGN, n = 43), and antineutrophil cytoplasmic antibody-associated GN (ANCA-GN, n = 26) based on a constellation of clinicopathologic features, but 101 cases (group X) could not be definitively differentiated. The reasons have been elucidated, most important being atypical combination of clinicopathologic features and lack of definitive evidence of active infection. Follow-up (on 72/101 cases) revealed that clinicians' working diagnosis was IgAN in 43%, SAGN/IRGN in 22%, ANCA-GN in 28%, and others in 7% of the cases, but treatment approach varied from supportive or antibiotics to immunosuppression in each subgroup. Comparing these cases as "received immunosuppression" versus "non-immunosuppression," only 2 features differed, namely C3-dominant staining, and possibility of recent infection (both higher in the no-immunosuppression group) (P < 0.05). Renal loss was higher in the non-immunosuppression subgroup, but not statistically significant (P = 0.11). Conclusion: Diagnostic overlap may remain unresolved in a substantial number of kidney biopsies with glomerular crescents and IgA deposits. A case-by-case approach, appropriate antibiotics if infection is ongoing, and consideration for cautious immunosuppressive treatment for progressive renal dysfunction may be needed for best chance of renal recovery.

Triple hit to the kidney-dual pathological crescentic glomerulonephritis and diffuse proliferative immune complex-mediated glomerulonephritis: A case report.

BACKGROUND: Anti-glomerular basement membrane (GBM) disease is a rare rapidly progressive glomerulonephritis, frequently associated with alveolar hemorrhage in the lungs and involving the kidney by crescentic glomerulonephritis. It has been described in association with other glomerulonephritides [such as anti-neutrophilic antibody (ANCA)-glomerulonephritis, membranous nephropathy, and immunoglobulin (Ig)A nephropathy]. CASE SUMMARY: Herein we present an unusual case of concurrent anti-GBM disease, ANCA-associated crescentic glomerulonephritis and diffuse proliferative immune complex mediated glomerulonephritis with predominant staining for IgA and C3 by immunofluorescence. The patient is a 46-year-old Caucasian male who presented to the emergency department with acute onset of flank pain and was found to have high serum creatinine levels of 15 mg/dL, proteinuria, and hematuria. He rapidly deteriorated and became anuric. He was found to have high anti-GBM antibodies titers (151 units) and high anti-neutrophil cytoplasmic-ANCA. Despite prompt and early treatment, the patient's condition worsened, and he succumbed to his illness. CONCLUSION: Our case emphasizes the importance of a renal biopsy in anti-GBM disease, even in the presence of positive serum anti-GBM antibodies, to identify other potential causes of rapidly progressive glomerulonephritis. The challenge in treating such cases lies in the different therapy modalities.

Role of protease-activated receptor-1 (PAR-1) in the glomerular filtration barrier integrity.

Protease-activated receptors (PAR) play an important role in the regulation of cellular function by the coagulation system, and they are activated by thrombin. PAR-1 is expressed in both endothelial cells and podocytes in the kidney. The role of PAR1 in the maintenance of the glomerular filtration barrier is not clear. Anticoagulant-related nephropathy (ARN) is a kidney disease with glomerular hematuria and red blood cell tubular casts. We validated 5/6 nephrectomy (5/6NE) in rats as a model of ARN and had demonstrated that direct thrombin inhibitor (dabigatran) induces ARN. The aim of this study was to investigate the role of PAR-1 in the ARN pathogenesis. 5/6NE rats were treated with dabigatran (150 mg/kg/day), PAR-1 inhibitor SCH79797 (1 and 3 mg/kg/day) and PAR-1 agonist TFLLR-NH2 (0.25 and 0.50 µmol/kg/day) for 7 days. Serum creatinine and hematuria were assessed daily. Kidney morphology was evaluated at the end of the study. In 5/6NE rats treated with either dabigatran or combination with a PAR-1 modulator, there was an elevation in serum creatinine, glomerular hematuria, red blood casts in the tubules, and acute tubular epithelial cell injury. Interestingly, both PAR-1 modulators in a dose-depended manner had similar effects on the serum creatinine levels and hematuria as those of dabigatran. Dabigatran-induced increase in the systolic blood pressure was not affected by PAR-1 modulators. In conclusion, the normal function of PAR-1 is crucial to maintain the glomerular filtration barrier integrity. Either activation or blockage of PAR-1 leads to glomerular hematuria and subsequent acute tubular epithelial cell injury.

Can Antinuclear Antibodies (ANA) be Monoclonal?

BACKGROUND: Nuclear staining by immunofluorescence in a kidney biopsy is often seen in patients with positive antinuclear antibodies (ANA) in the serum. These ANA are usually polyclonal, but herein we report 9 cases with an unusual finding of monoclonal nuclear staining by immunofluorescence on kidney biopsy. Case Presentation. Nine cases with predominant stain for kappa or lambda light chain were identified by searching the renal pathology laboratory database for the past 10 years. All cases had positive stain for only kappa (six cases) or lambda (three cases) light chain in the nuclei. Eight out of nine cases had positive nuclear IgG stain, and one case had positive nuclear IgA stain. Among cases with positive nuclear IgG staining, six cases were positive for IgG1 subclass, one case was positive for IgG2 subclass, and one case was positive for IgG3 subclass. All patients with positive IgG nuclear stain, who had testing for ANA, had positive ANA. Patients with positive IgG1 subclass did not have monoclonal protein in the serum or urine, but the patient with positive IgG2 subclass and lambda light chain stain in the nuclei had IgG lambda monoclonal gammopathy. CONCLUSIONS: We identified a new unique pattern of nuclear stain by immunofluorescence in kidney biopsies that suggests the presence of monoclonal ANA. Workup for underlying monoclonal gammopathy is warranted in such patients.

Chronic Hematuria Increases Chronic Kidney Injury and Epithelial-Mesenchymal Transition in 5/6 Nephrectomy Rats.

Chronic kidney disease (CKD) is a common outcome of many kidney diseases. Interstitial fibrosis and tubular atrophy (IFTA) is a histologic hallmark of CKD. Hematuria is a common symptom in many human kidney diseases. Free hemoglobin may affect tubular epithelial cells by generating reactive oxygen species (ROS). Epithelial-mesenchymal transition (EMT) of the tubular epithelial cells has been shown to play an important role in the IFTA development. The aim of this study was to determine the effects of chronic hematuria on the CKD progression in 5/6 nephrectomy (5/6NE) rat model of CKD. 5/6 NE rats were treated with oral warfarin (0.5 mg/kg/day) or vehicle (control). The animals were monitored for 26 weeks, while prothrombin time (PT), serum creatinine (SCr), and hematuria were measured weekly. Staining for iron, trichrome, and EMT (vimentin, E-cadherin, smooth muscle actin) markers was performed on the remnant kidneys. ROS were detected in the kidneys by protein carbonyl assay and immunohistochemistry for heme oxygenase 1 (HMOX1), at the end of the study. Apoptosis was detected by TUNEL assay. Warfarin treatment resulted in a PT increase 1.5-2.5 times from control and an increase in hematuria and SCr. Histologically, warfarin-treated animals had more iron-positive tubular epithelial cells and increased IFTA as compared to control (42.9 ± 17% vs. 18.3 ± 2.6%). ROS were increased in the kidney in warfarin-treated rats. The number of tubules that show evidence of EMT was significantly higher in warfarin-treated 5/6NE as compared to control 5/6NE rats. The number of apoptotic tubular epithelial cells was higher in warfarin-treated 5/6 NE rats. Chronic hematuria results in increased iron-positive tubular epithelial cells, EMT, apoptosis, and more prominent IFTA in CKD rats. Our data suggest an important role of chronic hematuria in the progression of CKD.

Hypertension and the Kidney: Reduced Kidney Mass Is Bad for Both Normotensive and Hypertensive Rats.

BACKGROUND: Hypertension is a leading cause of chronic kidney disease worldwide. Early studies demonstrated the short-term effects of hypertension on kidney function and morphology in ablative nephropathy. The aim of this study was to investigate the long-term consequences of hypertension in 5/6 nephrectomy (5/6NE) model. METHODS: Reduction of the kidney mass by 5/6NE was created in spontaneous hypertensive rats (SHR) and genetically similar normotensive Wistar Kyoto (WKY) rats. Blood pressure, serum creatinine (SCr), hematuria, and proteinuria were monitored weekly for 23 weeks. Kidney morphology was assessed at the end of the study. Sham-operated rats from both strains were used as controls. RESULTS: Rats with 5/6NE had increased SCr, blood pressure, hematuria, and proteinuria in both SHR and WKY. Even though the SCr levels and blood pressure were greater in 5/6NE SHR as compared with 5/6NE WKY rats, absolute changes from sham-operated rats were not statistically significant between these 2 groups. 5/6NE SHR had earlier onset and higher proteinuria than 5/6NE WKY rats. Hematuria was similar in 5/6NE SHR and 5/6NE WKY rats. However, 5/6NE SHR had enlarged glomeruli, increased interstitial fibrosis, and prominent intimal thickening in the small arteries/arterioles as compared with 5/6NE WKY rats. CONCLUSIONS: The long-term severity of kidney injury correlated with higher blood pressure. Reduction of the kidney mass increases SCr, hematuria, proteinuria, and blood pressure in both normotensive and hypertensive rats. Histological assessment provides better information about underlying chronic kidney injury than actual changes in SCr and urinalysis.