Role of the mechanisms for antibody repertoire diversification in monoclonal light chain deposition disorders: when a friend becomes foe

The adaptive immune system of jawed vertebrates generates a highly diverse repertoire of antibodies to meet the antigenic challenges of a constantly evolving biological ecosystem. Most of the diversity is generated by two mechanisms: V(D)J gene recombination and somatic hypermutation (SHM). SHM introduces changes in the variable domain of antibodies, mostly in the regions that form the paratope, yielding antibodies with higher antigen binding affinity. However, antigen recognition is only possible if the antibody folds into a stable functional conformation. Therefore, a key force determining the survival of B cell clones undergoing somatic hypermutation is the ability of the mutated heavy and light chains to efficiently fold and assemble into a functional antibody. The antibody is the structural context where the selection of the somatic mutations occurs, and where both the heavy and light chains benefit from protective mechanisms that counteract the potentially deleterious impact of the changes. However, in patients with monoclonal gammopathies, the proliferating plasma cell clone may overproduce the light chain, which is then secreted into the bloodstream. This places the light chain out of the protective context provided by the quaternary structure of the antibody, increasing the risk of misfolding and aggregation due to destabilizing somatic mutations. Light chain-derived (AL) amyloidosis, light chain deposition disease (LCDD), Fanconi syndrome, and myeloma (cast) nephropathy are a diverse group of diseases derived from the pathologic aggregation of light chains, in which somatic mutations are recognized to play a role. In this review, we address the mechanisms by which somatic mutations promote the misfolding and pathological aggregation of the light chains, with an emphasis on AL amyloidosis. We also analyze the contribution of the variable domain (V_L) gene segments and somatic mutations on light chain cytotoxicity, organ tropism, and structure of the AL fibrils. Finally, we analyze the most recent advances in the development of computational algorithms to predict the role of somatic mutations in the cardiotoxicity of amyloidogenic light chains and discuss the challenges and perspectives that this approach faces.

Abstract 3204: Differential expression of angiogenesis-associated genes in smoker and non-smoker lung adenocarcinoma patients

Tobacco smoke (TS) is one of the most prominent risk factors for lung and several other malignancies. Toxic chemicals present in TS induce DNA damage leading to carcinogenic mutations. Moreover, TS can also cause epigenetic and gene expression changes in tumor and other cells of the tumor microenvironment, especially through its addictive component nicotine. We and others have reported that nicotine promotes tumor angiogenesis via its direct impact on the endothelial cells or by altering the cancer cell secretome. In this study, we wanted to explore the association of smoking habits with the differential expression of angiogenesis-related genes in lung adenocarcinoma (LUAD) patients. Gene Set Enrichment Analysis (GSEA) identified a set of 48 angiogenesis-related genes that were surveyed for differential expression in smoker versus non-smoker patients in The Cancer Genomic Atlas (TCGA) database using an interactive web application, UALCAN. Gender and age of the LUAD patients were considered as confounding variables since patients of different age groups and gender can have biological and physiological differences, which could influence gene expression regardless of the smoking habits. We identified a total of fourteen differentially-expressed genes, of which four (HTATIP2, NCL, SPHK1, and VEGFA) were overexpressed and ten (AGGF1, AMOT, C1GALT1, ERAP1, NPR1, PML, RNH1, SHH, SPINL5, and TNFSF12) were downregulated in LUAD of smokers than those of non-smokers. Five of the differentially-expressed genes (HTATIP2, NCL NPR1, PML, and TNFSF12) exhibited significantly different transcript levels in males versus females and three (SPHK1, AGGF1, and SPINK5) showed varying pattern of expression in LUAD of different age group patients. Literature survey found prior published evidence for an association of two of the fourteen differentially expressed genes (NCL and NPR) with nicotine exposure. Together, our findings identify smoking-associated angiogenic gene signatures that could be potential effectors of nicotine signaling that promotes cancer angiogenesis and should be validated further by conducting laboratory investigations.

Citation Format: Shubhangi Singh, Santanu Dasgupta, Elba A. Turbat-Herrera, Seema Singh, Ajay P. Singh. Differential expression of angiogenesis-associated genes in smoker and non-smoker lung adenocarcinoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3204.

Glomerulopathic Light Chain-Mesangial Cell Interactions: Sortilin-Related Receptor (SORL1) and Signaling

INTRODUCTION

Deciphering the intricacies of the interactions of glomerulopathic Ig light chains with mesangial cells is key to delineate signaling events responsible for the mesangial pathologic alterations that ensue.

METHODS

Human mesangial cells, caveolin 1 (CAV1), wild type (WT) ,and knockout (KO), were incubated with glomerulopathic light chains purified from the urine of patients with light chain-associated (AL) amyloidosis or light chain deposition disease. Associated signaling events induced by surface interactions of glomerulopathic light chains with caveolins and other membrane proteins, as well as the effect of epigallocatechin-3-gallate (EGCG) on the capacity of mesangial cells to intracellularly process AL light chains were investigated using a variety of techniques, including chemical crosslinking with mass spectroscopy, immunofluorescence, and ultrastructural immunolabeling.

RESULTS

Crosslinking experiments provide evidence suggesting that sortilin-related receptor (SORL1), a transmembrane sorting receptor that regulates cellular trafficking of proteins, is a component of the receptor on mesangial cells for glomerulopathic light chains. Colocalization of glomerulopathic light chains with SORL1 in caveolae and also in lysosomes when light chain internalization occurred, was documented using double immunofluorescence and immunogold labeling ultrastructural techniques. It was found that EGCG directly blocks c-Fos cytoplasmic to nuclei signal translocation after interactions of AL light chains with mesangial cells, resulting in a decrease in amyloid formation.

CONCLUSION

Our findings document for the first time a role for SORL1 linked to glomerular pathology and signaling events that take place when certain monoclonal light chains interact with mesangial cells. This finding may lead to novel therapies for treating renal injury caused by glomerulopathic light chains.

Tubular Injury and Dendritic Cell Activation Are Integral Components of Light Chain-Associated Acute Tubulointerstitial Nephritis

CONTEXT.—

Light chain-associated acute tubulointerstitial nephritis (LC-ATIN) is a variant of light chain proximal tubulopathy (LCPT). It is characterized by interstitial inflammation with tubulitis and deposition of monoclonal light chains in the tubulointerstitium. LC-ATIN is a rather poorly recognized pattern of LCPT and not much is known about this entity.

OBJECTIVE.—

To determine the clinicopathologic features of patients with LC-ATIN and investigate the proximal tubular injury and mechanism of interstitial inflammation in LC-ATIN.

DESIGN.—

A total of 38 cases of LC-ATIN were identified from the archives of 5043 renal biopsy specimens. In all cases, routine light microscopic examination, immunofluorescence, and electron microscopic examination were performed. In selected cases, immunofluorescent staining of dendritic cells and immunohistochemical staining for 4 tubular injury markers-KIM-1, p53, bcl-2, and Ki-67-were performed.

RESULTS.—

A characteristic finding in LC-ATIN cases was immunofluorescence staining of monoclonal light chains along tubular basement membranes in linear fashion and inside proximal tubular cells with a granular pattern. No monoclonal light chains were present in glomerular or vascular compartments confirmed with immunofluorescence, electron microscopy, and ultrastructural gold labeling. Ten of 15 LC-ATIN cases (67%) were concurrently positive for the 4 tubular injury markers. Dendritic cells were identified within the tubulointerstitium in the renal biopsy specimens, interacting with surrounding tubules with light-chain deposits and inflammatory cells.

CONCLUSIONS.—

Significant proximal tubular injury occurs associated with LC-ATIN, and the monoclonal light chains accumulated in proximal tubular cells contribute to the injury. Dendritic cells are involved in the pathogenesis of interstitial inflammation in LC-ATIN.

Cystathione β-Synthase Is Increased in Thyroid Malignancies

BACKGROUND

Cystathione β-synthase (CBS) catalyzes the conversion of homocysteine and cysteine to hydrogen sulfide (H₂S) and cystathione, via the trans-sulfuration pathway. CBS protein expression levels are increased in several different human malignancies, with increased protein expression correlating with parameters such as tumor stage, anaplasia, metastases, and chemotherapy resistance.

MATERIALS AND METHODS

This study employed tissue microarrays to examine CBS expression in benign thyroid tissue, thyroid oncocytomas, thyroid follicular adenomas, and in follicular, papillary, anaplastic, and medullary thyroid carcinomas.

RESULTS

CBS expression was increased in all thyroid carcinomas types compared to benign thyroid tissue, but not in thyroid follicular adenomas or oncocytomas. A similar pattern was observed for nicotinamide phosphoribosyltransferase (NAMPT) tissue microarray analysis comparing thyroid adenomas and follicular carcinomas.

CONCLUSION

For the first time, we showed that an H₂S-syntheszing enzyme plays a role in thyroid malignancies. Additionally, our data suggest that CBS and NAMPT immunohistochemistry may be useful in differentiating follicular adenomas from follicular carcinomas.

Phenotypic plasticity of mesenchymal stem cells is crucial for mesangial repair in a model of immunoglobulin light chain-associated mesangial damage

Mesangiopathies produced by glomerulopathic monoclonal immunoglobulin light chains (GLCs) acting on the glomerular mesangium produce two characteristic lesions: AL-amyloidosis (AL-Am) and light chain deposition disease (LCDD). In both cases, the pathology is centered in the mesangium, where initial and progressive damage occurs. In AL-Am the mesangial matrix is destroyed and replaced by amyloid fibrils and in LCDD, the mesangial matrix is increased and remodeled. The collagen IV rich matrix is replaced by tenascin. In both conditions, mesangial cells (MCs) become apoptotic as a direct effect of the GLCs. MCs were incubated in-vitro with GLCs and animal kidneys were perfused ex-vivo via the renal artery with GLCs, producing expected lesions, and then mesenchymal stem cells (MSCs) were added to both platforms. Each of the two platforms provided unique information that when put together created a comprehensive evaluation of the processes involved. A "cocktail" with growth and differentiating factors was used to study its effect on mesangial repair. MSCs displayed remarkable phenotypic plasticity during the repair process. The first role of the MSCs after migrating to the affected areas was to dispose of the amyloid fibrils (in AL-Am), the altered mesangial matrix (in LCDD) and apoptotic MCs/debris. To accomplish this task, MSCs transformed into facultative macrophages acquiring an abundance of lysosomes and endocytotic capabilities required to engage in phagocytic functions. Once the mesangial cleaning was completed, MSCs transformed into functional MCs restoring the mesangium to normal. "Cocktail" made the repair process more efficient.

Oral foregut duplication cysts: A rare and fascinating congenital lesion. Case report and review of the literature

Oral foregut duplication cysts are extremely rare lesions with approximately 57 cases reported. They are congenital cysts, located in the anterior or ventral tongue, and occur predominantly in males. They are lined by one or more types of epithelia which is limited to gastric, intestinal or respiratory epithelium. The differential diagnosis includes lymphangioma, hemangioma, ranula, epidermoid cyst, teratoma and less likely a malignant process.

Healing the damaged mesangium in nodular glomerulosclerosis using mesenchymal stem cells (MSCs): Expectations and challenges

It has been shown experimentally that mesenchymal stem cells (MSCs) can be delivered to the mesangium in some conditions such as amyloidosis to clear debris and foreign material, and eventually transform into functional mesangial cells (MCs) and change the altered mesangial areas into normal collagen IV-rich matrix. A more challenging situation is when the matrix is rich in abnormal extracellular matrix proteins, especially those difficult to destroy such as tenascin, and, as a result, assumes a nodular appearance - what is known in pathology jargon as nodular glomerulosclerosis. MSCs find it difficult to dispose of the altered mesangial constituents, an initial step required for mesangial repair to occur successfully. The ability of MSCs to repair damaged mesangium represents a novel therapeutic intervention to reverse mesangial injury and is potentially a powerful and unique approach to prevent progression ending in end-stage renal disease (ESRD). This review will highlight progress that has been made in glomerular, and more specifically mesangial, repair, and will address future expectations and challenges to be confronted as the use of MSCs continues to be explored as a potential application for clinical practice.

Immunotactoid Glomerulopathy and Cryoglobulinemic Nephropathy: Two Entities with Many Similarities. A Unified Conceptual Approach

Immunotactoid glomerulopathy is a rare disorder that has been characterized at the ultrastructural level. Due to its rarity, there are few comprehensive studies relating to this disorder. Electron microscopy essentially characterizes this disease. The glomerular electron dense deposits which are typical of this condition consist of aggregates of highly organized microtubular structures of various diameters, but generally measuring 30-50 nm in width with a propensity to dispose themselves in parallel bundles intersecting in different planes. This study compares a large series of patients with cryoglobulinemic nephropathy with a series of patients with immunotactoid glomerulopathy to address whether there may be similarities that warrant considering these two entities part of a spectrum. This study reviews the clinicopathologic features of both entities and emphasizes ultrastructural findings that characterize them. Significant immunomorphologic overlap was found when these two disorders were compared in this study. There were also striking similarities in clinical presentation/behavior, laboratory findings and prognosis. Proteomic analysis has also demonstrated similar spectra for both entities. We postulate that immunotactoid glomerulopathy and cryoglobulinemic nephropathy are part of the spectrum of renal manifestations in patients with circulating cryoglobulins and renal disease.

Animal Models of Light Chain Deposition Disease Provide a Better Understanding of Nodular Glomerulosclerosis

BACKGROUND

Light chain deposition disease (LCDD) is a model of glomerulosclerosis. The mature lesion of LCDD mimics nodular glomerulosclerosis in diabetic nephropathy. The pathogenetic mechanisms involved are similar in both disorders, though the causative factors are entirely different. This fact highlights the generic response of the mesangium to varied stimuli. In-vitro work has provided much insight into the pathogenesis of glomerulosclerosis in LCDD where the mesangium is the main target for initiation and progression of the disease. The lack of animal models has prevented the development of further therapeutic approaches to be tested in platforms such as ex-vivo and in-vivo preparing the way for human studies.

METHODS

Light chains (LCs) obtained from the urine of patients with renal biopsy proven LCDD were delivered to glomeruli using ex-vivo and in-vivo approaches to address whether in-vitro information could be validated in-vivo. Selected in-vitro studies were conducted to address specific issues dealing with mesangial cell (MC) differentiation and composition of extracellular matrix to add additional data to the existing vast literature. Using light, electron and scanning microscopy together with immunohistochemistry and ultrastructural immunolabeling, MCs incubated in Matrigel with LCDD LCs, as well as delivery of such LCs by perfusion via renal artery (ex-vivo) and penile dorsal vein (in-vivo) to the kidneys, validation of pathogenetic pathways previously suggested in in-vitro experiments were tested and confirmed.

RESULTS

The animal models described in this manuscript provide validation for the in-vitro data that have been previously published and expand our appreciation of the important role that caveolin-1 plays in signaling events essential for the downstream sequence of events that eventually leads to the pathological alterations centered in the mesangium characterized by an increase in matrix production and formation of mesangial nodules.

CONCLUSIONS

The same findings observed in renal biopsies of patients with LCDD (mesangial expansion with increased matrix) were documented in the ex-vivo and in-vivo platforms. In-vivo understanding of the pathogenesis of mesangial glomerulosclerosis, as accomplished in the reported research, is crucial for the design of novel therapeutic approaches to treat a number of glomerulopathies with similar pathogenetic mechanisms. Inhibiting interactions between glomerulopathic LCs and MCs or interrupting the protein production/secretion pathways are potentially effective therapeutic maneuvers. The results obtained with caveolin-1 knockout mice emphasized the importance of caveolin-1 in signaling events essential to effect downstream mesangial alterations.

Neuroendocrine tumors in the ovary: histogenesis, pathologic differentiation, and clinical presentation

OBJECTIVE

Primary neuroendocrine tumors in the ovary are rare. These tumors arise from the neuroendocrine cell system of ovarian stroma and surface epithelium, and may also arise from teratoma. We present four primary ovarian neuroendocrine tumors and compare clinicopathologic findings based on tumor histogenesis and site of origin.

DESIGN

Four primary ovarian neuroendocrine tumors were identified from our 10-year departmental archives. H&E slides and immunostains were reviewed and the diagnoses were confirmed. Clinical history, imaging studies, and follow-up data were obtained from medical records.

RESULTS

Patients' ages ranged from 26 to 63. All patients presented with abdominal discomfort and unilateral or bilateral ovarian masses. MRI and CT scans from cases 1 and 2 revealed a solid ovarian mass with no extra-ovarian extension. In case 1, the patient also had a cystic mass in the opposite ovary and an elevated urine 5-HIAA. Microscopically, case 1 revealed a well-differentiated carcinoid tumor with no surface epithelial involvement, and a mature teratoma in the contralateral ovary. Case 2 revealed a stromal carcinoid within the ovarian parenchyma. Imaging studies from cases 3 and 4 showed large complex masses with peritoneal implants and ascites. In both cases 3 and 4, tumor grossly involved both ovarian parenchyma and surface epithelium with multiple pelvic implants. In addition, liver metastases were present in case 4. Microscopically, these tumors were poorly differentiated carcinoma with neuroendocrine differentiation. Histologic sections revealed extensive necrosis, and both cases showed positivity for neuroendocrine markers.

CONCLUSIONS

Primary neuroendocrine tumors in the ovary are rare and consist of a group of heterogeneous malignancies that express similar immunohistochemical markers. Primary neuroendocrine tumors that are limited to the ovarian parenchyma often arise from ovarian stroma and teratoma, and are carcinoid tumors with a good prognosis. Neuroendocrine tumors that arise from surface epithelium or dedifferentiate from de novo carcinoma often involve both ovarian stroma and surface epithelium and clinically present as aggressive malignancies with poor prognoses.

Comparison of in vivo probe-based confocal laser endomicroscopy with histopathology in lung cancer: A move toward optical biopsy

BACKGROUND AND OBJECTIVE

The development of novel technologies has increased the yield from transbronchial biopsies while preserving patient safety by guiding biopsies to the area of interest. Other technologies have helped identify pre-cancerous or sessile lesions in the endobronchial space by utilizing interactions between tissue and light at varying wavelengths. Probe-based confocal laser endomicroscopy (pCLE) is a new technology that encompasses the benefits of both guided biopsies and novel optical imaging in one device. This project compares pCLE images to the findings of light microscopy in non-small cell lung cancer (NSCLC).

METHODS

Patients who underwent bronchoscopies between July 2012 and January 2013 for evaluation of pulmonary lesions (transbronchial and endobronchial) were recruited. Histopathological images from malignant lesions were compared with the pCLE images obtained from the same area. The microscopic and pCLE images were reviewed side by side with the microscopic findings.

RESULTS

Images from pCLE correlate with some histopathological findings. pCLE changes seen in NSCLC consist of mottled elastin, septal studding and disorganization/fragmentation with increased friability. These changes also seem to correlate with degrees of differentiation.

CONCLUSIONS

pCLE can identify changes to the elastin composition of the airways and alveoli in lung cancer. These changes correlate with histopathology and may help indicate the presence of malignant changes in vivo.

The many faces of cryoglobulinemic nephropathy: a clinico-pathologic study of 47 cases with emphasis on the value of electron microscopy

The clinical and pathologic manifestations of cryoglobulinemic nephropathy (CN) are heterogeneous. The role that electron microscopy plays in the diagnosis of CN has not been properly evaluated. The main objective of this study was to define the value of ultrastructural evaluation in the diagnosis of CN. Although most of the CN cases in this series exhibited glomerular pathology with a membranoproliferative pattern, a significant number of the cases showed less well-defined morphologic patterns on light microscopic examination (i.e. mesangial proliferation, hyaline thrombi in glomerular capillaries without significant cellular proliferation, exudative glomerulonephritis, etc). Immunofluorescence microscopy also revealed variable immunoglobulin and complement component patterns, some with "full-house" expression of immunoreactants. A subset of these CN cases was associated with light chain restriction. Thus, differential diagnosis can be a challenge as many other glomerulonephritis overlap in immunomorphologic characteristics. Because the immunomorphologic manifestations of CN are so varied, confirmation of a suspected diagnosis of CN or making a diagnosis in a less than a typical immunomorphologic setting required careful ultrastructural evaluation to find unequivocal diagnostic findings or at least supportive evidence in the form of detection of substructure in the electron dense glomerular deposits consistent with cryoglobulins. Even in cases where the light and immunofluorescence findings in suspicious clinical situations were quite consistent with CN, electron microscopy provided the final proof to substantiate the diagnosis in the great majority of the cases.

Renal diseases with organized deposits: an algorithmic approach to classification and clinicopathologic diagnosis

CONTEXT

Most renal diseases with organized deposits are relatively uncommon conditions, and proper pathologic characterization determines the specific diagnosis. Different entities with specific clinical correlates have been recognized, and their correct diagnosis has an impact on patient management, treatment options, and determination of prognosis.

OBJECTIVE

The diagnosis of these conditions depends on careful evaluation of the findings by light microscopy together with immunofluorescence and electron microscopy. The objective of this manuscript is to delineate an algorithmic approach helpful in the pathologic assessment of these conditions at the light microscopic level. In some diseases, the immunomorphologic parameters short of electron microscopy provide solid information to suggest or make a definitive diagnosis. Nevertheless, electron microscopy plays a crucial role, because the criteria to separate these entities often are heavily influenced by the electron microscopic findings. Accepted diagnostic criteria for each of these conditions are discussed.

DESIGN

Information used for this manuscript is gathered from published data and the authors' experience.

RESULTS

The most common of these conditions is amyloidosis, which may account for as many as 5% to 8% of all renal biopsies in some renal pathology practices. Fibrillary, immunotactoid, and cryoglobulinemic glomerulopathies together represent, at most, 1% of all renal biopsies performed for medical renal diseases. Diabetic fibrillosis also is uncommon. Glomerulopathies associated with fibronectin deposits and collagenofibrotic glomerulopathy are extremely rare.

CONCLUSIONS

A systematic, algorithmic approach to the evaluation of the renal biopsies from patients with these disorders is very helpful to rule out certain conditions in the early stages of the evaluation of the biopsies. However, it is not uncommon for the final definitive diagnosis to be reached only after electron microscopic evaluation.

The Use of Electron Microscopy to Refine Diagnoses in the Daily Practice of Cytopathology

Conceived as a screening tool, cytology is a field that since the 1980s has become more diagnostic in its scope. The advent of the fine-needle aspiration biopsy (FNAB) is responsible for cytology's new place in pathology. In the everyday practice of cytopathology, about 85-90% of the nongynecologic cases can be diagnosed with the use of routine stains (i.e., Papanicolaou and Diff Quik). The other 10-15% of the cases require the use of ancillary diagnostic techniques for a precise diagnosis. Immunohistochemistry helps solve approximately 50% of these cases, and the other half of these challenging cases are best approached and diagnosed by using electron microscopy (EM). In their practice, the authors obtain cytologic samples for EM routinely in difficult cases. Unfortunately, a percentage of these cases collected for ultrastructural evaluation do not have enough cells after processing, and others only have a few diagnostic cells available. In the cases in which at least a handful of cells are available, EM is almost invariably helpful in one way or another, either making a definitive diagnosis or refining the diagnosis. A sampling of FNAB cases from the authors' everyday practice is prevented to illustrate the use of EM in the practice of cytopathology. The cases have been selected from among the most common diagnostic challenges to highlight the important role that ultrastructural evaluation plays in a busy cytology practice. In our practice ultrastructural evaluation is a piece of the puzzle, which, along with the clinical history, clinical impression, light microscopic/cytologic features, and other ancillary techniques (IHC, flow cytometry, and molecular pathology), help compile an accurate diagnosis. Many times EM is the most important component of the diagnostic algorithm.

Electron Microscopy in the Diagnosis of BK-Polyoma Virus Infection in the Transplanted Kidney

BK polyomavirus has become an important etiologic agent responsible for significant morbidity in renal transplant recipients. This virus can be detected in transitional cells in the urine (decoy cells) using cytology, but correlation with allograft function status and histologic evidence of renal involvement is poor. Accurate diagnosis of BK polyomavirus infection requires a high index of suspicion and utilization of ancillary diagnostic techniques in many cases. Electron microscopy is very sensitive in depicting the presence of BK virions, but the finding of viral particles is not by itself diagnostic of BK interstitial nephritis. Management of patients with polyoma virus nephropathy is difficult since there is no specific antiviral therapy available at this time.

Electron Microscopy Renders the Diagnostic Capabilities of Cytopathology More Precise: An Approach to Everyday Practice

Cytology is a powerful diagnostic tool but to make definitive diagnoses, the use of ancillary techniques is imperative. By combining immunohistochemistry (IHC) and electron microscopy (EM), cytologic diagnoses can be as precise as those of surgical pathology. In the authors' daily practice of cytopathology they use all ancillary techniques available to them: histochemistry, IHC, EM, flow cytometry, and molecular pathology. IHC is frequently used as an ancillary technique in their daily practice but EM is many times their technique of choice. By the use of EM the authors can make specific final diagnoses, make the diagnosis more definitive, narrow the differential diagnosis, or determine the origin of a neoplasm with unknown primary site. Specimens obtained by fine-needle aspiration as well as all body fluids are suitable for EM. The limiting factor is to obtain the appropriate material with the diagnostic cells for ultrastructural examination. The common diagnostic dilemmas in the everyday practice of cytology are the following: mesothelioma vs. adenocarcinoma, neuroendocrine differentiation or not, the distinction of melanoma from adenocarcinoma and sarcoma, hepatocellular carcinoma vs. adenocarcinoma, and the origin of adenocarcinomas of unknown primary. The authors discuss how they approach these diagnostic problems in their everyday practice and how they incorporate EM in solving them.

BK Polyomavirus in Renal Transplants: Role of Electron Microscopy and Immunostaining in Detecting Early Infection

Reactivation of BK polyomavirus (BKV) is increasingly recognized as a cause of failure of renal allografts. Since no specific treatment is available for this infection, early diagnosis is important, as it allows for early intervention and possible recovery of renal function. Forty-four consecutive renal transplant biopsies performed over a 2-year period were included in the study. In addition to evaluation of renal biopsy tissue sections using routine histochemical stains, CD3, CD20, BK virus immunostains using the specific BK virus and the SV40 antibodies and electron microscopy studies were performed. None of the transplant cases but one exhibited classical histologic viral changes. Viral particles were seen by EM in 19%, and BK-virus positivity was identified in only 43% of these cases. CD20-rich inflammatory infiltrates predominated in cases in which either positive BK stain and/or viral particles were identified ultrastructurally. A combined approach using electron microscopic and immunohistochemical evaluation can be utilized effectively to identify BK virus-associated nephropathy at an early phase facilitating early clinical intervention.

EGFR expression as an ancillary tool for diagnosing lung cancer in cytology specimens

Lung cancer evolves in a multistep process, and its early detection portends a better prognosis. Bronchial washings/brushings and fine-needle aspirations are often used as early screening and cytological diagnosis of lung cancer. In some cases, it is difficult to differentiate morphologically malignant from reactive cells. Epidermal growth factor receptor (EGFR) is a transmembrane receptor overexpressed in high percentage lung cancers, and contributes to tumor growth. Assessing EGFR expression levels by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) may provide critical information of tumor marker abnormalities, assist in the cytological diagnosis, and stratify patients for EGFR inhibitor therapy. Fifty patients with bronchial washings/brushings or fine-needle aspiration specimens, and corresponding histologically confirmed lung biopsies, were studied for EGFR expression with FISH and IHC. Copy numbers of the EGFR gene locus were analyzed with those of chromosome 7 by FISH. EGFR and FISH results were compared to our FISH data with combined EGFR, c-myc, 5p15.2, and chromosome 6 probes in selected cases. Cell blocks, if available, and tissue biopsy sections were used for EGFR IHC. The intensity of IHC was scored, and quantified. Only balanced aneuploidy of EGFR was identified by FISH. Gene amplification was not detected. The chromosomal abnormalities of EGFR were often accompanied by other chromosomal aneuploidies demonstrated in c-myc (8q24), 5p15.2 or 6p, indicating a general genomic instability. About half of the specimens with confirmed malignancy showed EGFR balanced aneuploidy by FISH, and gene copy number was not coupled with protein expression in many cases. The benign or reactive cytology specimens confirmed by biopsies had high specificity by FISH (96%) and IHC (88%). FISH and IHC analysis of EGFR, possibly along with other tumor markers, may be a useful ancillary tool to classify difficult cytology cases and inform clinicians arranging targeted chemotherapy.

Role of translational research advancing the understanding of the pathogenesis of light chain-mediated glomerulopathies

Glomerulopathic light chains engage in pathological interactions with mesangial cells resulting in alterations in glomerular homeostasis. The crucial pathological events are centered in the mesangium and, therefore, research dealing with pathogenesis of these disorders is focused on this glomerular compartment. Particular physicochemical characteristics of these light chains are responsible for their ability to alter mesangial milieu leading to glomerular damage. An in vitro model has been used to dissect the processes involved. This model has been instrumental in providing a solid platform from which to observe in a dynamic fashion how mesangial cells handle pathogenic light chains and the sequential steps that are involved in the progressive glomerular damage. Key steps amenable to possible modulation have been defined and should provide a solid platform to design and test therapeutic interventions. In the past significant difficulties have been encountered in the development of animal models of light chain-induced glomerular damage. However, in the last few years a new generation of animal models has emerged to address whether what has been documented in vitro retains significance in vivo. Preliminary observations appear to substantiate this.

Association between HLA-DQB1 and cervical dysplasia in Vietnamese women

Host genetic background seems to play a key role in cervical carcinogenesis as only a small subset of women infected with high-risk human papillomaviruses (HPVs) develop cervical cancer. The rate of cervical cancer in Vietnamese women is notably high. To explore the association of human leukocyte antigen (HLA)-DQB1 alleles, HPV infection, and cervical dysplasia in this population, cervical smears were obtained from 101 women attending the obstetrics and gynecology clinic of Da Nang General Hospital in Vietnam. Besides the Papanicolaou test, HPV and HLA-DQB1 genotyping were performed using cervical smear DNA. Additionally, a subset of 30 blood samples was used as the gold standard for HLA genotyping. HLA-DQB1 alleles showed no association with HPV infection status. However, a positive association with cervical dysplasia was found for HLA-DQB1*0302 (P= 0.0229, relative risk (RR) = 4.737) and HLA-DQB1*0601 (P= 0.0370, RR = 4.038), whereas HLA-DQB1*0301 (P= 0.0152, RR = 0.221) was found negatively associated. The low diversity of HLA-DQB1 alleles, wide spectrum of HPV genotypes, and high prevalence of HPV 16 and HPV 18 observed in the study population suggest a permissive/susceptible genetic background that deserves further research. Total concordance of HLA-DQB1 genotyping results between blood and cervical cells confirms the potential value of cervical smears as an effective tool for the development of cervical cancer biomarkers.

eIF4E as a Marker for Cervical Neoplasia

Eukaryotic translation initiation factor 4E (eIF4E) is upregulated in cancers of the breast and head and neck. The authors have shown that eIF4E is increased in cervical neoplasia and that eIF4E upregulates human papillomavirus (HPV) oncoprotein E7. The aim of this study was to quantitate eIF4E in tissues representing a wide range of cervical pathology. The potential correlation between dysplastic grade or tumor stage with eIF4E upregulation and/or HPV genotype was analyzed for 10 normal, 27 cancer, and 37 dysplasia cases. A progressive increase in eIF4E staining intensity was found with increasing cervical pathology (P < 0.0001). No difference was seen in eIF4E stain intensity by either tumor type--squamous cell cancer (n = 18), adenocarcinoma (n = 4), or other types of cancer (n = 5) (P = 0.97)--or by tumor grade--II (n = 5) versus III (n = 7). Likewise, neither an HPV typing result of HPV 16 (n = 10) versus non-HPV 16 (n = 4) nor single HPV infection (n = 11) versus dual HPV infection (n = 3) significantly altered the eIF4E stain results (P = 0.86 and 0.97, respectively). These results indicate that eIF4E stain intensity may be useful as a marker for cervical neoplasia.

Human papillomavirus typing of rare cervical carcinomas

CONTEXT

Most cervical tumors are classified as squamous cell carcinoma or adenocarcinoma, both of which are associated with persistent human papillomavirus (HPV) infection. Although other (rare) types represent less than 5% of all cervical carcinomas, it is necessary that these more unusual tumors be studied in the current era of papillomavirus vaccine development, especially in regions with high incidence of cervical cancer.

OBJECTIVE

To compare papillomavirus types found in histologically rare cervical carcinomas (n = 29) with those types found in common cervical carcinomas (n = 14) archived at the Institute of Cancer in Mexico City, Mexico.

DESIGN

Paraffin-embedded tissues were received and sectioned at the Louisiana State University Health Sciences Center at Shreveport. One section for each block was stained and examined by 2 pathologists. Specific histologies were categorized into 2 broad groups: common (squamous cell carcinoma or adenocarcinoma) or rare (adenosquamous, papillary, villoglandular, anaplastic, transitional, spindle, adenoid basal, colloid, neuroendocrine, and glassy cell carcinomas). Papillomavirus typing results were based on Roche Molecular Systems line-blot assay.

RESULTS

No significant difference was found for dual HPV types (21% of both groups), positivity for HPV-16 (66% of rare tumors and 71% of common tumors), or absence of HPV types 16 or 18, although the rare cancers had a greater tendency toward more unusual HPV types (8/29 rare tumors and 1/14 common tumors had no HPV- 16 or HPV-18 DNA). Non-HPV-16/18 types found only in rare tumors included HPV types 52, 84, 26, 35, and 58.

CONCLUSIONS

Rare types of cervical carcinoma also are associated with papillomavirus, most with types similar to those found in common cervical neoplasias.

Human papillomavirus detection: verification with cervical cytology

OBJECTIVE

Thirteen specific types of human papillomavirus (HPV), classified as high-risk for the development of cervical cancer, have been reported in 99.7% of all cervical cancers. For this reason, and because of the reported lack of sensitivity of the Papanicolaou (Pap) smear for detecting HPV, some experts believe that the use of papillomavirus DNA testing may replace cytology for routine gynecological screening. Our goal was to validate a commercial assay, the Digene Hybrid Capture-2 for the detection of human papillomavirus by comparing the results to cytological detection of cervical abnormalities.

DESIGN

Cytology results of concurrent liquid-based Papanicolaou smears were compared to the Hybrid Capture-2 results. Correlation was assessed and discordant cytology results were reviewed.

SETTING

Louisiana State University Health Sciences Center at Shreveport, Department of Pathology, HPV Diagnostic Laboratory.

PATIENTS

All liquid cytology specimens submitted for HPV testing between November 1, 2000 and April 1, 2001.

RESULTS

Of the 291 cases tested by Hybrid Capture-2, 12% and 28% were positive with the low-risk and high-risk probes, respectively, and 265 had concurrent cytology results. Fourteen specimens testing positive only with the low-risk probe were not included in this comparison. Thus, the results for 251 of the 291 (86%) specimens tested for human papillomavirus DNA were compared to the original cytology report. Overall concordance between Hybrid Capture-2 and the original smear cytology result was 78%. Slide review reduced the number of discordant specimens from 22% to 12%.

CONCLUSION

Based upon these data, we find the HPV assay to be useful as a routine screen for Human papillomavirus.

Hepatoblastoma in a 15-month-old male: cytomorphology, electron microscopy, and differential diagnosis

The authors describe a case of hepatoblastoma in a 15-month-old male and discuss the differential diagnosis and electron microscopic features of small round cell tumors. The patient was found to have an enlarged liver and was admitted to the hospital for further investigation. Fine-needle aspiration of the liver revealed small. uniform cells with increased nuclear/cytoplasmic ratio and focal rosette formation. A diagnosis of small blue cell neoplasm favoring hepatoblastoma was made, but neuroblastoma could not be ruled out. Electron microscopic analysis performed on the liver aspirate showed features of hepatic differentiation as well as absence of neuroblastic differentiation. The diagnosis of hepatoblastoma was made. Serum alpha-fetoprotein level of 33,250 mg/L confirmed the diagnosis. Liver biopsy performed subsequently showed tumor cells arranged in nests, acini, and trabeculae with mitotic figures. Electron microscopy showed the same findings as described above. The patient underwent chemotherapy for 4 months and subsequently a partial liver resection was performed. This case illustrates the important role of electron microscopy in evaluating small round cell tumors in children.

Evaluation of fluorescence in situ hybridization as an ancillary tool to urine cytology in diagnosing urothelial carcinoma

Our purpose was to evaluate the feasibility of performing fluorescence in situ hybridization (FISH) on routine urine samples and to compare the relative sensitivities of urine cytology and FISH for detecting urothelial carcinoma. Light microscopy (LM) using cytologic evaluation and FISH were used to study 121 consecutive urine samples. A mixture of fluorescent probes to chromosomes 3, 7, 17, and the 9p21 locus were used for detection of numerical chromosomal abnormalities (UroVysion, Vysis/Abbott). Biopsy specimens from patients in the study were reviewed if available. FISH analysis was performed without knowledge of cytology or biopsy findings. The urine cytology of 121 samples was interpreted as 59 negative, 41 reactive, 16 atypical, 2 suspicious and 3 insufficient cells for diagnosis. 85 samples were successfully analyzed by FISH. Thirty-one of these showed chromosomal abnormalities and these samples were initially regarded on the original cytology reading as follows: 10 negative, 10 reactive, 9 atypical, and 2 suspicious. FISH demonstrated chromosomal abnormalities in a significant number of cases (67%) that were initially diagnosed as normal or reactive by LM. Twenty-five patients were identified who had biopsy-proven TCC and successful FISH. Thirteen of the 25 patients (52%) were abnormal by FISH (cytology: 2 suspicious, 6 atypical, 4 reactive, 1 negative). One patient was atypical by cytology with normal FISH results but had TCC on biopsy. Hyperdiploidy for chromosomes 3 (77%) and 7 (67%) were seen consistently. Multiple chromosomal abnormalities were seen in 67% of these cases. We conclude that FISH has a greater sensitivity in detecting urothelial carcinoma when coupled with urine cytology. It is not entirely clear at this time whether a positive FISH may indicate frank neoplastic urothelial transformation or merely be an indicator of unstable urothelium capable of or primed for malignant transformation thus detecting patients at significant risk. The use of FISH in conjunction with urine cytology can potentially reduce urothelial carcinoma morbidity and mortality by diagnosing these tumors earlier.

Current role of electron microscopy in the diagnosis of pigmented tumors

Melanoma represents the most diagnostically challenging of the group of pigmented lesions to be discussed in this review, but a number of other pigmented lesions may present diagnostic difficulties either because they are uncommon or occur in unexpected clinico-pathologic situations. With the routine use of immunohistochemistry as the initial ancillary diagnostic technique in surgical pathology, electron microscopy has been relegated to a secondary but still essential diagnostic role in a significant number of these cases. There are no stains that are 100% specific or sensitive in depicting these lesions. The practice of using immunohistochemistry first (and in many laboratories exclusively) to address diagnostic dilemmas, although appearing to be a practical and cost-effective approach, is not always the case. Once 3 or more antibodies are used to solve the diagnostic challenge, ultrastructural evaluation becomes less expensive. To solve a difficult diagnostic problem often requires testing for 4 to 5 antigens. Turn around times for both immunohistochemistry and electron microscopy are similar. Ultra-rapid (3 hours) processing of specimens for electron microscopy is available for those cases requiring immediate diagnosis. One genuine problem with using immunohistochemistry as the initial diagnostic technique is that the results may show staining patterns that can be regarded as consistent with the diagnosis of melanoma even when the diagnosis is incorrect, and the need for performing ultrastructural evaluation is never appreciated. Immunohistochemistry and electron microscopy should be considered truly complementary and it is unfortunate that utilization of both diagnostic modalities does not occur more frequently. Pathologists should be aware of the entire immuno-morphological spectrum associated with melanocytic neoplasms to be able to address diagnostic difficulties that may, arise as a consequence of the heterogeneity of these tumors.

Expression of the translation initiation factor eIF4E in the polyp-cancer sequence in the colon

The eukaryotic translation initiation factor 4E (eIF4E) has been shown to play a key role in cell growth, and several studies have documented an increased expression of eIF4E in a number of solid tumors, including breast, bladder, cervical, and head and neck cancers. This study was done to evaluate the potential role of eIF4E in the polyp-cancer sequence in the colorectum. Eighty-seven cases with lesions in the colorectum with a variety of histopathological diagnoses were randomly selected from the archives of the Pathology Department at Louisiana State University Health Sciences Center-Shreveport. Appropriate sections were selected for immunostaining with eIF4E. The medical records of the patients were reviewed, and demographic information was collected. All statistical analyses were performed using SAS software. A statistically significant relationship was found between the level of eIF4E expression and histological type of lesion: the lowest level of eIF4E expression was found in normal colon tissue, whereas the highest level of eIF4E expression was found in colorectal adenocarcinomas. Carcinomatous lesions were found to have a 43 times higher chance of having a high level of eIF4E expression compared with normal tissue (95% confidence interval, 8.0-213.6, P < 0.0001). In a multivariate analysis, histological type was the only variable that showed a significant relationship with eIF4E expression; no effect was found due to age, gender, race, history of polyps, and family history. The results from this study are consistent with other data from the literature and support the suggestion that eIF4E is strongly involved in colon tumorigenesis. eIF4E might be a useful intermediate biomarker for use in chemoprevention intervention studies in patients with colorectal polyps.

The ultrastructural and immunohistochemical heterogeneity of CD-30-positive neoplasms: so-called anaplastic large cell Ki-1 lymphomas

Anaplastic large cell lymphoma (ALCL), also referred to as Ki-1 lymphomas, was first recognized as an entity with characteristic light microscopic appearance in 1985. This tumor is composed of variably cohesive cells, often with large, markedly atypical, and multinucleated cellular forms. The recognition of ALCL resulted from the development of a monoclonal antibody in Kiel, Germany, named Ki-1, which was initially believed to be a putative marker for Reed-Sternberg cells. This antibody was later found to be specific against the epitope CD-30. Attempts to create strict criteria to preserve this neoplasm as a specific entity have undergone evolution. However, it is now clear that included in this group are a variety of pleomorphic neoplasms with CD-30 immunoreactivity. Some of these neoplasms are nonlymphoid and show marked heterogeneity in their immunohistochemical and ultrastructural profiles. This article aims to highlight the ultrastructural spectrum of neoplasms exhibiting CD-30 positivity that are within the spectrum of ALCL. It remains to be determined if there are subgroups of these CD-30-positive neoplasms that can be segregated on the basis of ultrastructural and immunohistochemical criteria with corresponding clinical correlates that may impact on their management, treatment, and prognosis. We review here the heterogeneity of CD-30-positive neoplasms (so-called anaplastic large cell Ki-1 lymphomas).

Placebo-controlled trial of indole-3-carbinol in the treatment of CIN

OBJECTIVE

Most precancerous lesions of the cervix are treated with surgery or ablative therapy. Chemoprevention, using natural and synthetic compounds, may intervene in the early precancerous stages of carcinogenesis and prevent the development of invasive disease. Our trial used indole-3-carbinol (I-3-C) administered orally to treat women with CIN as a therapeutic for cervical CIN.

METHODS

Thirty patients with biopsy proven CIN II-III were randomized to receive placebo or 200, or 400 mg/day I-3-C administered orally for 12 weeks. If persistent CIN was diagnosed by cervical biopsy at the end of the trial, loop electrocautery excision procedure of the transformation zone was performed. HPV status was assessed in all patients.

RESULTS

None (0 of 10) of the patients in the placebo group had complete regression of CIN. In contrast 4 of 8 patients in the 200 mg/day arm and 4 of 9 patients in the 400 mg/day arm had complete regression based on their 12-week biopsy. This protective effect of I-3-C is shown by a relative risk (RR) of 0.50 ((95% CI, 0. 25 to 0.99) P = 0.023) for the 200 mg/day group and a RR of 0.55 ((95% CI, 0.31 to 0.99) P = 0.032) for the 400 mg/day group. HPV was detected in 7 of 10 placebo patients, in 7 of 8 in the 200 mg/day group, and in 8 of 9 in the 400 mg/day group.

CONCLUSIONS

There was a statistically significant regression of CIN in patients treated with I-3-C orally compared with placebo. The 2/16 alpha-hydroxyestrone ratio changed in a dose-dependent fashion.

Immunoelectron microscopy in the age of molecular pathology

The introduction of molecular biology-based diagnostic procedures in pathology has created substantial expectations in regard to screening, characterization, monitoring, and detection of predisposition to a variety of diseases, most notably malignant neoplasms. It should be emphasized, however, that molecular studies are only one component of the diagnostic process and that more traditional methods are still required in the evaluation of tumors and management of patients. The data obtained from the molecular biology-based studies must be always interpreted in conjunction with the clinical history, immunomorphologic findings, and other pertinent ancillary data. Routine evaluation of tissues using traditional light microscopy remains the backbone of pathologic evaluation. The additive role of molecular diagnostics often depends on how accurate the initial evaluation has been. Ancillary techniques such as immunohistochemistry and electron microscopy remain essential in properly characterizing diseased tissues and in speciation of tumors. Ultrastructural immunolabeling capitalizes on combining these two techniques and providing exquisite immunomorphologic evaluation. The extra time and effort required are more than compensated by the degree of sophistication that can be achieved when this diagnostic technique is utilized and the added expense is rather reasonable. The value of molecular biology-based diagnostics is potentially questionable if the tissue samples are not initially accurately characterized. The question that molecular diagnostics may be trying to answer may be the wrong one or the answer obtained may be interpreted incorrectly if the context of the clinicopathologic situation has not been clearly defined using traditional diagnostic techniques.