Nephronophthisis: a pathological and genetic perspective.

Nephronophthisis (NPHP) is an autosomal recessive cystic kidney disease and is one of the most frequent genetic causes for kidney failure (KF) in children and adolescents. Over 20 genes cause NPHP and over 90 genes contribute to renal ciliopathies often involving multiple organs. About 15-20% of NPHP patients have additional extrarenal symptoms affecting other organs than the kidneys.

Renal Hypoplasia, From Grossly Insufficient to Not Quite Enough: Consideration for Expanded Concepts Based Upon the Author's Perspective With Historical Review.

Hypoplasia is defined in the Merriman-Webster dictionary as "a condition of arrested development in which an organ, or part, remains below the normal size, or in an immature state." The degree of reduced size is not definitional. Renal hypoplasia, however, has historically been defined as a more marked reduction in renal mass such that presentation in childhood is the norm.

Urologic Diseases Germane to the Medical Renal Biopsy: Review of a Large Diagnostic Experience in the Context of the Renal Architecture and Its Environs.

The kidney is one of the most complicated organs in development and is susceptible to more types of diseases than other organs. The disease spectrum includes developmental and cystic diseases, involvement by systemic diseases, iatrogenic complications, ascending infections and urinary tract obstruction, and neoplastic diseases. The diagnosis of kidney disease is unique involving 2 subspecialties, urologic pathology and renal pathology.

Fluorescence in situ hybridization for the diagnosis of NPHP1 deletion-related nephronophthisis on renal biopsy.

Nephronophthisis is an autosomal recessive tubulointerstitial nephropathy that is a leading genetic etiology of end-stage renal disease in children and young adults. Approximately 60% of patients with a known genetic etiology of nephronophthisis are due to homozygous deletion of the NPHP1 gene. We identified a total of 45 renal biopsies from young patients with chronic kidney disease of undetermined etiology and analyzed them for the possibility of nephronophthisis due to NPHP1 deletion using interphase fluorescence in situ hybridization and/or polymerase chain reaction.

Challenges in Pathologic Staging of Renal Cell Carcinoma: A Study of Interobserver Variability Among Urologic Pathologists.

Staging criteria for renal cell carcinoma differ from many other cancers, in that renal tumors are often spherical with subtle, finger-like extensions into veins, renal sinus, or perinephric tissue. We sought to study interobserver agreement in pathologic stage categories for challenging cases. An online survey was circulated to urologic pathologists interested in kidney tumors, yielding 89% response (31/35).

An integrated pathology and ultrasonography-based simulation for training in performing kidney biopsy .

Background: Medical practice trends and limitations in trainees' duty hours have diminished the interest and exposure of nephrology fellows to percutaneous kidney biopsy (PKB). We hypothesized that an integrated nephrology-pathology-led simulation may be an effective educational tool.

Materials And Methods: A 4-hour PKB simulation workshop (KBSW), led by two ultrasonography (US)-trained nephrologists and two nephropathologists, consisted of 6 stations: 1) diagnostic kidney US with live patients, 2) kidney pathology with plasticine models of embedded torso cross-sections, 3) US-based PKB with mannequin (Blue Phantom™), 4) kidney pathology with dissected cadavers, 5) US-based PKB in lightly-embalmed cadavers, and 6) tissue retrieval adequacy examination by microscope.

Tuberous sclerosis complex: Hamartin and tuberin expression in renal cysts and its discordant expression in renal neoplasms.

Tuberous sclerosis complex (TSC) results from mutation of TSC1 or TSC2 that encode for hamartin and tuberin. It affects the kidneys often in advance of extra-renal stigmata. We studied 14 TSC cases, and 4 possible TSC cases with multiple angiomyolipomas (AMLs) for hamartin and tuberin protein expression to determine if the staining profile could predict mutation status or likelihood of TSC with renal-limited disease.

Lack of electron microscopy hinders correct renal biopsy diagnosis: A study from India.

Electron microscopy (EM) is performed routinely on all native kidney biopsies in the western world. However, in India, it is not regularly performed due to non-availability and financial constraints. The aim of this prospective study was to evaluate the usefulness of routinely performing EM on native kidney biopsies.

Vascular mesangial channels in human nodular diabetic glomerulopathy.

The presence of vascular mesangial channels has been reported in idiopathic nodular glomerulosclerosis and diabetic glomerulopathy. However, only limited information on the morphology and immunohistochemical phenotype of these channels is available. This study aims to describe the light and electron microscopic features of these channels and delineate their immunohistochemical phenotype.

Eosinophilic, Solid, and Cystic Renal Cell Carcinoma: Clinicopathologic Study of 16 Unique, Sporadic Neoplasms Occurring in Women.

A unique renal neoplasm characterized by eosinophilic cytoplasm and solid and cystic growth was recently reported in patients with tuberous sclerosis complex (TSC). We searched multiple institutional archives and consult files in an attempt to identify a sporadic counterpart. We identified 16 morphologically identical cases, all in women, without clinical features of TSC.

[Renal tumors: The International Society of Urologic Pathology (ISUP) 2012 consensus conference recommendations].

During the last 30 years many advances have been made in kidney tumor pathology. In 1981, 9 entities were recognized in the WHO Classification. In the latest classification of 2004, 50 different types have been recognized.

Membranous-like glomerulopathy with masked IgG kappa deposits.

The diagnostic classification of glomerulonephritis is determined by the interplay of changes seen using light, immunofluorescence, and electron microscopy of the renal biopsy. Routine direct immunofluorescence on fresh tissue is currently considered the gold standard for the detection and characterization of immune deposits. We recently found a peculiar form of glomerular immune complex deposition in which masked deposits required an antigen-retrieval step to be visualized.

Handling and staging of renal cell carcinoma: the International Society of Urological Pathology Consensus (ISUP) conference recommendations.

The International Society of Urologic Pathology 2012 Consensus Conference on renal cancer, through working group 3, focused on the issues of staging and specimen handling of renal tumors. The conference was preceded by an online survey of the International Society of Urologic Pathology members, and the results of this were used to inform the focus of conference discussion. On formal voting a ≥65% majority was considered a consensus agreement.

Polymer embolization from minimally invasive interventions.

Many of the tools used in interventional nephrology, such as glidewires and sheaths, are coated with a hydrophilic polymer to increase their lubricity; however, this polymer can shear off, which causes polymer embolization. We describe 3 cases in which polymer emboli were found on histopathologic examination in an arteriovenous graft, a transplanted kidney, and the myocardium. A review of the literature shows that although most of these phenomena are benign, in some patients, it may present with significant morbidity.

Localized cystic disease of the kidney: distinction from cystic neoplasms and hereditary polycystic diseases.

Cystic changes are common in both neoplastic and non-neoplastic kidney diseases. The most important diagnostic consideration is to rule out cystic neoplasms and hereditary polycystic kidney disease for patient management. Localized cystic disease of the kidney is a rare, nongenetic and nonprogressive cystic disease that may mimic cystic neoplasms or hereditary polycystic disease.

Retrograde venous invasion in renal cell carcinoma: a complication of sinus vein and main renal vein invasion.

Renal cell carcinoma, especially clear cell, gains access to the venous system as the initial route of extrarenal spread. Intravenous growth can involve extrarenal veins or renal veins in other portions of the kidney, referred to herein as retrograde venous invasion. This study investigates the incidence and defines the pathological features of retrograde venous invasion.

The non-neoplastic kidney in tumor nephrectomy specimens: what can it show and what is important?

Surgical nephrectomy is a procedure that has been performed for nearly 100 years. In the presence of a normal contralateral kidney, such as in a renal transplant donor or child with Wilms tumor, it is a benign procedure without deleterious consequences on the remaining kidney. However, many adults and some children postnephrectomy will develop chronic kidney disease.

The classification of renal cystic diseases and other congenital malformations of the kidney and urinary tract.

Context: Renal cystic diseases and congenital abnormalities of the kidney and urinary tract comprise a heterogeneous group of lesions whose pathogenesis has eluded physicians for centuries. Recent advances in molecular and genetic understanding of these diseases may provide the solution to this riddle.

Objective: The formulation of an effective classification system for these disorders has been elusive but is needed to introduce order while providing a conceptual framework for diagnosis.

The Oxford IgA nephropathy clinicopathological classification is valid for children as well as adults.

To study the predictive value of biopsy lesions in IgA nephropathy in a range of patient ages we retrospectively analyzed the cohort that was used to derive a new classification system for IgA nephropathy. A total of 206 adults and 59 children with proteinuria over 0.5 g/24 h/1.

Renal cystic diseases and renal neoplasms: a mini-review.

The past two decades have witnessed recognition of several new types of renal cell carcinoma, each with distinct cytogenetic abnormalities. Included are several genetic and acquired cystic kidney diseases associated with development of renal cell carcinoma, the topic of this review. The risk in patients with autosomal dominant polycystic kidney disease is not accurately known but may be slightly increased.

The Oxford classification of IgA nephropathy: rationale, clinicopathological correlations, and classification.

IgA nephropathy is the most common glomerular disease worldwide, yet there is no international consensus for its pathological or clinical classification. Here a new classification for IgA nephropathy is presented by an international consensus working group. The goal of this new system was to identify specific pathological features that more accurately predict risk of progression of renal disease in IgA nephropathy, thus enabling both clinicians and pathologists to improve individual patient prognostication.

The Oxford classification of IgA nephropathy: pathology definitions, correlations, and reproducibility.

Pathological classifications in current use for the assessment of glomerular disease have been typically opinion-based and built on the expert assumptions of renal pathologists about lesions historically thought to be relevant to prognosis. Here we develop a unique approach for the pathological classification of a glomerular disease, IgA nephropathy, in which renal pathologists first undertook extensive iterative work to define pathologic variables with acceptable inter-observer reproducibility. Where groups of such features closely correlated, variables were further selected on the basis of least susceptibility to sampling error and ease of scoring in routine practice.

Lymphatic differentiation in renal angiomyolipomas.

Renal angiomyolipomas are mesenchymal neoplasms with varying proportions of smooth muscle, adipose tissue, and abnormal blood vessels. Although the presence of lymphangiomatous-like foci is frequently noted in large series of angiomyolipoma, lymphatic differentiation has not been previously studied. Twelve angiomyolipomas from 10 patients were identified.

Interphase cytogenetic analysis with centromeric probes for chromosomes 1, 2, 6, 10, and 17 in 11 tumors from a patient with bilateral renal oncocytosis.

Renal oncocytosis is characterized by the presence of multiple tumors with oncocytic features, often associated with small clusters of tubule-like structures with oncocytic change. The morphologic features of the oncocytic nodules encompass a spectrum of appearances, with patterns typical of renal oncocytoma or classic chromophobe renal cell carcinoma, as well as 'hybrid' tumors with features resembling both oncocytoma and chromophobe renal cell carcinoma. We utilized interphase cytogenetic methods to study 11 tumors from the kidneys of a 45-year-old woman.