Search

Glomerular deposition of monoclonal IgM, frequently in the form of intracapillary pseudothrombi, can be seen in Waldenström macroglobulinemia (WM) and type I cryoglobulinemia (CG). They are typically associated with plasma cell or B-lymphoid neoplasms, particularly lymphoplasmacytic lymphoma (LPL). While infection is a frequent trigger of mixed (type II and III) CG, its association with type I CG is uncommon. We report two cases in which striking lambda-chain-restricted IgM deposits and acute kidney injury (AKI) occurred in the setting of known or suspected systemic infections, with prompt resolution on treatment of the infection. [ABSTRACT FROM AUTHOR]

Infection-related glomerulonephritis is well recognized in patients with ongoing infections. It can be missed, however, if the infection is unusual or undetected. We present three cases where the renal biopsy findings prompted the identification or treatment of systemic infections. Case 1: A 84-year-old male presented with acute kidney injury (AKI) and IgA vasculitis on skin biopsy. A renal biopsy showed active glomerulonephritis with abundant neutrophils and predominantly mesangial immune complex deposits containing IgA. The findings prompted an infectious workup which was positive for COVID-19, suggesting exacerbation of IgA nephropathy by recent COVID-19 infection. Case 2: A 31-year-old female status post kidney transplant for granulomatosis with polyangiitis (GPA) had recent pregnancy with preterm delivery, disseminated herpes simplex virus (HSV) infection with HSV hepatitis, E. coli on urine culture, and AKI. A renal biopsy showed proliferative glomerulonephritis with subendothelial and mesangial immune complex deposits containing IgG and C3. The findings were most consistent with infection-related immune complex glomerulonephritis, most likely HSV-related. Case 3: A 78-year-old female presented with AKI, proteinuria, hematuria, and positive p-ANCA. Clinically, ANCA vasculitis was suspected, and renal biopsy did show focal, segmental, necrotizing glomerulonephritis. However, immunofluorescence and electron microscopy showed IgM-rich deposits in the mesangium. The unusual presentation prompted an infectious workup including a Bartonella antibody panel which showed very high titers, suggesting Bartonella endocarditis. Infection-related glomerulonephritis has a wide variety of presentations histologically and clinically. The three cases we present here emphasize the importance of recognizing these entities to help guide treatment and improve patient care. [ABSTRACT FROM AUTHOR]

Electron microscopy is a mainstay in the analysis of renal biopsies, where it is typically employed in a correlative fashion along with light and immunofluorescence microscopy. Despite the development of a growing armamentarium of molecular and biochemical analytic methods as well as new immunostains with a widening panel of immunoreactants, electron microscopy remains crucial to the diagnosis of a number of disorders involving the renal glomerulus, vasculature, and tubulointerstitial compartment. The number of renal biopsies continues to grow and the indications for these biopsies continue expanding together with our understanding of disease processes. Proper collection of biopsies and careful analysis of data emanating from diagnostic modalities, clinical information, imaging, gross and microscopic tissue analysis, including a wide range of ancillary studies, represent the essential paradigm for generating detailed diagnoses with clinical significance. This communication offers a guide to the pre-analytic and analytic process for renal biopsy examination, discusses diagnostic keys and pitfalls for an important category of renal diseases (immune complex disorders), and provides an introduction to a useful adjunct diagnostic method (ultrastructural immunolabeling). Renal pathologists should render expert diagnoses that guide patient management, provide prognostic information and lead to targeted new therapeutic interventions that are currently available. [ABSTRACT FROM AUTHOR]

Kidney biopsy is a mainstay in the diagnosis and management of renal disease in patients with systemic lupus erythematosus. Though biopsies from patients with lupus typically show various forms of immune complex glomerulonephritis, other pathologies are occasionally encountered, including unusual lupus-related nephropathies, other forms of autoimmune disease, and occasional renal disorders without any direct connection with lupus or autoimmunity. Electron microscopy is a powerful tool for detecting and classifying these unusual conditions, which frequently have important therapeutic and prognostic implications. [ABSTRACT FROM AUTHOR]

Ultrastructural examination remains a crucial diagnostic tool for analysis of renal biopsies, along with light and immunofluorescence microscopy. Several advantages of electron microscopy are the ability to detect most forms of glomerular disease/dysfunction; the ability to examine small, suboptimal, or unusual specimens; and superior resolution that allows the investigator to hunt without preconceived ideas of what he/she is looking for or will find. A few shortcomings must be noted for completeness, including inability to detect disorders without specific ultrastructural signature, biochemical heterogeneity of deposits with similar or identical ultrastructural appearances, and occasional false-negative results in diseases with focal manifestations. [ABSTRACT FROM AUTHOR]

Organized or structured deposits are encountered during electron microscopic examination of kidney tissue in a wide variety of primary renal and multisystemic disorders. They are most commonly seen in the renal glomerulus, though extraglomerular sites are occasionally involved. In some cases, organized deposits herald the presence of a specific disease process. Included in this category are organized substances containing immunoglobin molecules or parts thereof as well as non-immunoglobin-containing materials that accumulate in several rare heritable disorders. A second broad category of structured deposits include substances that accumulate in response to non-specific tissue injuries. In many instances, such "look-alikes" can be difficult o distinguish from disease-specific structured deposits. Ultrastructural pathology is central to the detection and characterization of organized deposits in the kidney and is the primary focus of this paper. Correlative light microscopic studies are often useful, however, and will be described as well.. [ABSTRACT FROM AUTHOR]

Renal diseases involving glomerular deposits of fibrillary material are an important diagnostic challenge for the ultrastructural pathologist. Two primary disorders of this type, termed ``fibrillary glomerulonephritis'' (characterized by fibrils measuring approximately 20nm in diameter) and ``immunotactoid glomerulopathy'' (characterized by larger, microtubular deposits), have been described. The possible relatedness of these two disorders and their potential association with other systemic illnesses are subjects of current debate. Other multisystemic diseases, including amyloidosis and various forms of cryoglobulinemia, can also present with fibrillary or microtubular deposits in the kidney. Five cases are presented in which fibrillar or microtubular structures were identified in renal biopsies by ultrastructural examination. The distinction between fibrillary glomerulonephritis,immunotactoid glomerulopathy, and other processes that have similar ultrastructural features are discussed. [ABSTRACT FROM AUTHOR]

An abstract of the article "Renal biopsy in patients with lupus: Not just lupus nephritis!" by Jacques Gilloteaux and others, is presented.

Investigates the presence of fibrillary and lipid deposits in nephrotic syndrome. Use of ultrastructural and immunohistochemical for the diagnosis; Composition of the fibrils; Deposition of the fibrils within the glomerular mesangium and capillary loops.