Nontargeted Native Renal Biopsy Adequacy: Preintervention Data From a Province-Wide, Multicentre, and Interdepartmental Audit.

Background: Nontargeted renal biopsy is essential to diagnosis, classification, and prognostication of medical renal disease. Inadequate biopsies delay diagnosis, expose the patient to repeated biopsy, and increase costs. Objective: The purpose of this project is to characterize nontargeted renal biopsy specimen adequacy and identify areas for improvement. Design: This project was designed as a clinical audit of specimen adequacy rates of nontargeted renal biopsies from 13 hospitals, as well as a questionnaire of radiology and pathology department staff regarding current practices surrounding renal biopsies. Setting: Retrospective analysis of 2188 adult native renal biopsies was performed from January 1, 2018, to September 9, 2021, across 13 hospitals. Patients: Adult patients with medical renal disease undergoing a nontargeted renal biopsy were included. Methods: Retrospective analysis of 2188 adult native renal biopsies was performed from January 1, 2018, to September 9, 2021, across 13 hospitals. Adequacy was divided into 4 categories based on number of glomeruli received: ideally adequate (≥25 glomeruli), minimally adequate (15-24), suboptimal (<15 and diagnosis rendered), and inadequate (<15 and no diagnosis rendered). Two targets were chosen; target 1, to achieve a combined suboptimal and inadequate rate ≤ 10%, and target 2, to attain an ideally adequate rate ≥80%. Radiology department heads in the province were surveyed on biopsy equipment, technique, technologist support, and feasibility of possible interventions to enhance biopsy adequacy. Pathology department staff were surveyed on their education and experience. Results: Adequacy was as follows: ideally adequate 64.7%, minimally adequate 26.0%, suboptimal 7.9%, and inadequate 1.4%. The province (and 8/13 hospitals) met target 1 for native biopsies (9.3%). Two hospitals achieved target 2 for native biopsies. A key finding was that the 2 hospitals with the lowest target 1 scores did not have a technologist present at biopsy. Limitations: Survey data was used to assess biopsy technique at each hospital, and specific technique for each biopsy was not recorded. As such, a multivariate statistical analysis of specimen adequacy rates was not feasible. Data on complications was not collected. Conclusions: Preintervention the province was at target for limiting inadequate and suboptimal native biopsies. There was a substantial shortfall in the ideally adequate rate from the proposed target. Using insight from survey data, interventions with the greatest expected impact were identified and those that are feasible given limited resources will be implemented to improve sample adequacy. Trial Registration: Not registered.

Contexte: La biopsie rénale non ciblée est essentielle au diagnostic, à la classification et au pronostic d'une néphropathie. Les biopsies inadéquates retardent le diagnostic, exposent le patient à des biopsies répétées et coûtent plus cher au système de santé. Objectif: L'objectif de cette étude était de caractériser l'adéquation des échantillons des biopsies rénales non ciblées et de dégager les domaines d'amélioration. Conception: Cet essai a été conçu comme un audit clinique du taux d'adéquation des échantillons de biopsies rénales non ciblées provenant de 13 hôpitaux. Il comporte également un questionnaire destiné au personnel des services de radiologie et de pathologie portant sur les pratiques actuelles entourant les biopsies rénales. Cadre: Analyze rétrospective de 2 188 biopsies rénales natives réalisées chez des patients adultes dans 13 hôpitaux entre le 1er janvier 2018 et le 9 septembre 2021. Sujets: Ont été inclus les adultes atteints d'une pathologie rénale médicale ayant subi une biopsie rénale non ciblée. Méthodologie: Nous avons procédé à une analyze rétrospective de 2 188 biopsies rénales natives réalisées chez des patients adultes dans 13 hôpitaux entre le 1er janvier 2018 et le 9 septembre 2021. L'adéquation a été classée en 4 catégories en fonction du nombre de glomérules reçus: parfaitement adéquate (25 glomérules et plus), minimalement adéquate (15 à 24 glomérules), sous-optimale (moins de 15 glomérules + diagnostic rendu), inadéquate (moins de 15 glomérules sans diagnostic rendu). Deux objectifs ont été établis: obtenir un taux d'adéquation combiné « sous-optimale + inadéquate ¼ de 10 % ou moins (objectif 1) et obtenir au moins 80 % d'adéquation « parfaite ¼ (objectif 2). Les chefs des services de radiologie de la province ont été interrogés sur l'équipement de biopsie, la technique, le soutien des technologues et la faisabilité des interventions possibles visant à améliorer l'adéquation des biopsies. Le personnel des services de pathologie a été interrogé sur sa formation et son expérience. Résultats: Les taux d'adéquation étaient les suivants: parfaitement adéquate = 64,7 %; minimalement adéquate = 26,0 %; sous-optimale = 7,9 %; inadéquate = 1,4 %. Pour les biopsies natives, avec un taux de 9,3 %, la province (et 8 des 13 hôpitaux) a atteint l'objectif 1. Deux hôpitaux ont atteint l'objectif 2. Une des principales observations a été qu'il n'y avait aucun technologue présent lors de la biopsie dans les deux hôpitaux qui avaient obtenu les moins bons résultats pour l'objectif 1. Limites: Les données de l'enquête ont été utilisées pour évaluer la technique de biopsie dans chaque hôpital; la technique précise utilisée pour chaque biopsie n'a pas été consignée. Par conséquent, il n'était pas possible de réaliser une analyze statistique multivariée des taux d'adéquation des échantillons. Les données sur les complications n'ont pas été recueillies. Conclusion: Avant l'intervention la province atteignait déjà l'objectif de limiter des biopsies natives inadéquates et sous-optimales. Le taux d'adéquation jugé « parfaitement adéquat ¼ était nettement inférieur à l'objectif proposé. Les données de l'enquête ont permis d'identifier les interventions dont l'impact escompté est le plus important; celles qui sont réalisables compte tenu des ressources limitées seront mises en œuvre afin d'améliorer l'adéquation des échantillons.

A Diverse Spectrum of Immune Complex- and Complement-Mediated Kidney Diseases Is Associated With Mantle Cell Lymphoma.

Introduction: There are limited reports on kidney biopsy findings in patients with mantle cell lymphoma (MCL). Methods: We initiated a multi-institutional, retrospective review of kidney biopsy findings in patients with active and treated MCL. Results: A total of 30 patients with MCL and kidney biopsies were identified, with a median age of 67 (range 48-87) years, 73% of whom were men. A total of 20 patients had active MCL at the time of biopsy, of whom 14 (70%) presented with acute kidney injury (AKI), proteinuria and/or hematuria, and biopsy findings potentially attributable to lymphoma. Of the 14, 11 had immune complex (IC) or complement-mediated (C3) disease including proliferative glomerulonephritis (GN) with monotypic Ig deposits (PGNMID [2]), C3GN, (2), secondary membranous nephropathy (MN [3]), tubular basement membrane (TBM) deposits (2), and modest lupus-like GN (2). Lymphomatous infiltration was present in 8 of the 20 patients, 5 with coincident IC or C3 lesions. A total of 6 patients with available follow-up were treated for MCL, all with clinical remission of GN (2 PGNMID, 2 C3GN, and 2 MN). Conclusion: MCL is associated with diverse monoclonal and polyclonal glomerular and extra-glomerular IC and C3 disease. For patients with active MCL and kidney dysfunction requiring biopsy, 70% had findings due or potentially due to lymphoma, including 55% with IC or C3 disease and 40% had lymphomatous kidney infiltration. IC and C3GN in the setting of active MCL was responsive to lymphoma-directed therapy.

A Distributed System Improves Inter-Observer and AI Concordance in Annotating Interstitial Fibrosis and Tubular Atrophy.

Histologic examination of interstitial fibrosis and tubular atrophy (IFTA) is critical to determine the extent of irreversible kidney injury in renal disease. The current clinical standard involves pathologist's visual assessment of IFTA, which is prone to inter-observer variability. To address this diagnostic variability, we designed two case studies (CSs), including seven pathologists, using HistomicsTK- a distributed system developed by Kitware Inc. (Clifton Park, NY). Twenty-five whole slide images (WSIs) were classified into a training set of 21 and a validation set of four. The training set was composed of seven unique subsets, each provided to an individual pathologist along with four common WSIs from the validation set. In CS 1, all pathologists individually annotated IFTA in their respective slides. These annotations were then used to train a deep learning algorithm to computationally segment IFTA. In CS 2, manual and computational annotations from CS 1 were first reviewed by the annotators to improve concordance of IFTA annotation. Both the manual and computational annotation processes were then repeated as in CS1. The inter-observer concordance in the validation set was measured by Krippendorff's alpha (KA). The KA for the seven pathologists in CS1 was 0.62 with CI [0.57, 0.67], and after reviewing each other's annotations in CS2, 0.66 with CI [0.60, 0.72]. The respective CS1 and CS2 KA were 0.58 with CI [0.52, 0.64] and 0.63 with CI [0.56, 0.69] when including the deep learner as an eighth annotator. These results suggest that our designed annotation framework refines agreement of spatial annotation of IFTA and demonstrates a human-AI approach to significantly improve the development of computational models.

Distinct Functional Requirements for Podocalyxin in Immature and Mature Podocytes Reveal Mechanisms of Human Kidney Disease.

Dominant and recessive mutations in podocalyxin (PODXL) are associated with human kidney disease. Interestingly, some PODXL mutations manifest as anuria while others are associated with proteinuric kidney disease. PODXL heterozygosity is associated with adult-onset kidney disease and podocalyxin shedding into the urine is a common biomarker of a variety nephrotic syndromes. It is unknown, however, how various lesions in PODXL contribute to these disparate disease pathologies. Here we generated two mouse stains: one that deletes Podxl in developmentally mature podocytes (Podxl∆Pod) and a second that is heterozygous for podocalyxin in all tissues (Podxl+/-). We used histologic and ultrastructural analyses, as well as clinical chemistry assays to evaluate kidney development and function in these strains. In contrast to null knockout mice (Podxl-/-), which die shortly after birth from anuria and hypertension, Podxl∆Pod mice develop an acute congenital nephrotic syndrome characterized by focal segmental glomerulosclerosis (FSGS) and proteinuria. Podxl+/- mice, in contrast, have a normal lifespan, and fail to develop kidney disease under normal conditions. Intriguingly, although wild-type C57Bl/6 mice are resistant to puromycin aminonucleoside (PA)-induced nephrosis (PAN), Podxl+/- mice are highly sensitive and PA induces severe proteinuria and collapsing FSGS. In summary, we find that the developmental timepoint at which podocalyxin is ablated (immature vs. mature podocytes) has a profound effect on the urinary phenotype due to its critical roles in both the formation and the maintenance of podocyte ultrastructure. In addition, Podxl∆Pod and Podxl+/- mice offer powerful new mouse models to evaluate early biomarkers of proteinuric kidney disease and to test novel therapeutics.

IgA-dominant glomerulonephritis with a membranoproliferative pattern of injury.

Immunoglobulin A (IgA)-dominant membranoproliferative glomerulonephritis (MPGN) is a descriptive term for renal biopsies in which differential diagnoses of unusual IgA nephropathy (IgAN), infection-related GN, or other etiologies are considered. We sought to understand clinical and pathologic features of this finding. Native kidney biopsies with IgA-dominant immune deposits and diffuse MPGN features without significant exudative features or subepithelial deposits were retrospectively reviewed. Two groups (n = 27, 33 biopsies) were identified: patients with chronic liver disease and those without. Patients without chronic liver disease (n = 15) were men (73%, age 40) who presented with nephrotic-range proteinuria, hematuria, renal insufficiency, negative serologic studies, and no history of infection. At a median interval of 3 years, 11 had available follow-up information. Three (27%) progressed to end-stage renal disease. One had recurrent IgA-dominant GN in the renal allograft less than 1 year posttransplant. Four of 5 patients with repeat biopsies had persistent IgA-dominant MPGN. Patients with chronic liver disease (n = 12) had similar biopsy findings, but 42% had concurrent infections, some occult. At a median interval of 7 weeks, 8 patients (80% of those with follow-up) had died and 2 were dialysis dependent. In conclusion, IgA-dominant MPGN was seen in 2 clinical cohorts in this study. In patients without chronic liver disease, this appears to represent either a unique clinicopathologic entity with a poorer prognosis than IgAN or an aggressive variant of IgAN. Patients with chronic liver disease often have underlying infection, and regardless of treatment, die within 1 year because of complex medical conditions.

Acute kidney injury in children with sickle cell disease-compounding a chronic problem.

In an article recently published in Pediatric Nephrology, Baddam and colleagues discuss the relatively underreported clinical problem of repeated episodes of acute kidney injury (AKI) in children with sickle cell disease (SCD). Their report is a cautionary note about the importance of repeated kidney injury on the background of underlying chronic kidney injury and its potential implications on long-term kidney outcome. In children and adults with SCD, this includes the effects of repeated vaso-occlusive crises and the management of these painful episodes with non-steroidal anti-inflammatory drugs. Here we review the scope of kidney involvement in SCD in children and discuss the potential short- and long-term consequences of AKI in children with SCD.

Medullary Microvascular Thrombosis and Injury in Sickle Hemoglobin C Disease.

Sickle cell nephropathy is a common complication in patients with sickle cell hemoglobinopathies. In these disorders, polymerization of mutated hemoglobin S results in deformation of red blood cells, which can cause endothelial cell injury in the kidney that may lead to thrombus formation when severe or manifest by multilayering of the basement membranes (glomerular and/or peritubular capillaries) in milder forms of injury. As the injury progresses, the subsequent ischemia, tubular dysfunction, and glomerular scarring can result in CKD or ESRD. Sickle cell nephropathy can occur in patients with homozygous hemoglobin SS or heterozygous hemoglobin S (hemoglobin SC, hemoglobin S/ß(0)-thalassemia, and hemoglobin S/ß(+)-thalassemia). Clinical manifestations resulting from hemoglobin S polymerization are often milder in patients with heterozygous hemoglobin S. These patients may not present with clinically apparent acute sickle cell crises, but these milder forms can provide a unique view of the kidney injury in sickle cell disease. Here, we report a patient with hemoglobin SC disease who showed peritubular capillary and vasa recta thrombi and capillary basement membrane alterations primarily involving the renal medulla. This patient highlights the vascular occlusion and endothelial cell injury in the medulla that contribute to sickle cell nephropathy.

Spontaneous Hepatic Rupture Associated With Epstein-Barr Virus Negative Aggressive Natural Killer Cell Leukemia.

Aggressive natural killer cell leukemia (ANKL) is a rare subtype of large granular lymphocyte (LGL) leukemia, which typically presents in young adults of Asian descent. It is an aggressive disease, characterized initially by fever, pancytopenia and hepatosplenomegaly, which rapidly progresses to organ failure and death over the course of months. Spontaneous hemorrhagic complications have been reported to occur in ANKL in a handful of case reports, including lethal intestinal and cerebral hemorrhage as well as splenic rupture. Here, we present a case of a 49-year-old man with Epstein-Barr virus (EBV)-negative ANKL who developed fatal spontaneous hepatic rupture approximately 4 months after initial diagnosis. To the best of our knowledge, this is first reported case of hepatic rupture associated with ANKL.

A novel algorithm for simplification of complex gene classifiers in cancer.

The clinical application of complex molecular classifiers as diagnostic or prognostic tools has been limited by the time and cost needed to apply them to patients. Using an existing 50-gene expression signature known to separate two molecular subtypes of the pediatric cancer rhabdomyosarcoma, we show that an exhaustive iterative search algorithm can distill this complex classifier down to two or three features with equal discrimination. We validated the two-gene signatures using three separate and distinct datasets, including one that uses degraded RNA extracted from formalin-fixed, paraffin-embedded material. Finally, to show the generalizability of our algorithm, we applied it to a lung cancer dataset to find minimal gene signatures that can distinguish survival. Our approach can easily be generalized and coupled to existing technical platforms to facilitate the discovery of simplified signatures that are ready for routine clinical use.

The different morphologies of urachal adenocarcinoma do not discriminate genomically by micro-RNA expression profiling.

Urachal adenocarcinoma has several morphologic presentations that include mucinous, enteric, signet ring cell, and not otherwise specified. Mixtures of these morphologies can occur, and percentage cut-offs are used for classification. The clinical significance of these morphologic types is currently unknown, and genetic analysis that could elucidate possible intertumoral differences has not been performed. In this study, we analyzed the micro-RNA expression profiles of 12 urachal adenocarcinomas classified using strict morphologic criteria (3 pure enteric, 3 pure mucinous, 2 signet ring cell [both 90% signet ring cell], 2 pure not otherwise specified, and 2 mixed cell types). Of 598 unique human micro-RNAs, 333 were expressed in more than 50% of the samples. Hierarchal clustering showed no distinct patterns in the genetic profiles of the morphologic types. However, there were individual micro-RNA differences when the different types were compared individually or grouped together, either by intracellular mucin production or by grouping enteric and signet ring cell together. In the later group, 13 messenger RNA species were differentially expressed (adjusted P value of ≤.05). However, these micro-RNA differences were small, suggesting more biologic similarity than differences among these entities. Thus, this study suggests that the different morphological subtypes may represent patterns of differentiation or a continuum of a single biological tumor type rather than several distinct types that arose from the urachal remnant epithelium. This finding, if further validated in larger studies, may have implications in future clinical therapeutic trials for urachal adenocarcinoma with regard to patient grouping and choice of therapy.

Idiopathic pontine Streptococcus salivarius abscess in an immunocompetent patient: management lessons through case illustration and literature review.

A 55-y-old woman with no previous medical history presented with a 3-day history of progressive headache, nausea, emesis, right-sided facial numbness, and right-sided extremity weakness. Serial magnetic resonance imaging demonstrated rapid enlargement of a left-sided ring-enhancing dorsal pontine lesion with an exophytic portion, raising concern for an abscess. A stereotactically guided left-sided retrosigmoid craniotomy for abscess incision and decompression was performed given the rapid progression of her neurological deficits. Streptococcus salivarius was isolated from the intra-operative samples. After an extensive evaluation, no source for the S. salivarius was identified. Solitary brainstem abscesses are uncommon intracranial infections with high morbidity and mortality. Patients can present with non-specific symptoms and often have no previous medical history. Since 1974, 40 patients with solitary brainstem abscess have survived to hospital discharge. We outline management strategies for solitary brainstem abscess based on a literature review of survivors.

Functional analysis of the transmembrane domain in paramyxovirus F protein-mediated membrane fusion.

To enter cells, enveloped viruses use fusion-mediating glycoproteins to facilitate the merger of the viral and host cell membranes. These glycoproteins undergo large-scale irreversible refolding during membrane fusion. The paramyxovirus parainfluenza virus 5 mediates membrane merger through its fusion protein (F). The transmembrane (TM) domains of viral fusion proteins are typically required for fusion. The TM domain of F is particularly interesting in that it is potentially unusually long; multiple calculations suggest a TM helix length between 25 and 48 residues. Oxidative cross-linking of single-cysteine substitutions indicates the F TM trimer forms a helical bundle within the membrane. To assess the functional role of the paramyxovirus parainfluenza virus 5 F protein TM domain, alanine scanning mutagenesis was performed. Two residues located in the outer leaflet of the bilayer are critical for fusion. Multiple amino acid substitutions at these positions indicate the physical properties of the side chain play a critical role in supporting or blocking fusion. Analysis of intermediate steps in F protein refolding indicated that the mutants were not trapped at the open stalk intermediate or the prehairpin intermediate. Incorporation of a known F protein destabilizing mutation that causes a hyperfusogenic phenotype restored fusion activity to the mutants. Further, altering the curvature of the lipid bilayer by addition of oleic acid promoted fusion of the F protein mutants. In aggregate, these data indicate that the TM domain plays a functional role in fusion beyond merely anchoring the protein in the viral envelope and that it can affect the structures and steady-state concentrations of the various conformational intermediates en route to the final postfusion state. We suggest that the unusual length of this TM helix might allow it to serve as a template for formation of or specifically stabilize the lipid stalk intermediate in fusion.

Analysis of the pH requirement for membrane fusion of different isolates of the paramyxovirus parainfluenza virus 5.

Paramyxoviruses enter cells by fusing their envelopes with the plasma membrane, a process that occurs at neutral pH. Recently, it has been found that there is an exception to this dogma in that a porcine isolate of the paramyxovirus parainfluenza virus 5 (PIV5), known as SER, requires a low-pH step for fusion (S. Seth, A. Vincent, and R. W. Compans, J. Virol. 77: 6520-6527, 2003). As a low-pH activation mechanism for fusion would greatly facilitate biophysical studies of paramyxovirus-mediated membrane fusion, we have reexamined the triggering of the PIV5 SER fusion protein. Using multiple assays, we could not find a requirement for low-pH triggering of PIV5 SER fusion. The challenge of discovering how the paramyxovirus receptor binding protein (HN, H, or G) activates the metastable fusion protein to cause membrane fusion at neutral pH remains.