Guidelines for Pathologic Diagnosis of Mesothelioma

CONTEXT.—

Mesothelioma is an uncommon tumor that can be difficult to diagnose.

OBJECTIVE.—

To provide updated, practical guidelines for the pathologic diagnosis of mesothelioma.

DATA SOURCES.—

Pathologists involved in the International Mesothelioma Interest Group and others with expertise in mesothelioma contributed to this update. Reference material includes peer-reviewed publications and textbooks.

CONCLUSIONS.—

There was consensus opinion regarding guidelines for (1) histomorphologic diagnosis of mesothelial tumors, including distinction of epithelioid, biphasic, and sarcomatoid mesothelioma; recognition of morphologic variants and patterns; and recognition of common morphologic pitfalls; (2) molecular pathogenesis of mesothelioma; (3) application of immunohistochemical markers to establish mesothelial lineage and distinguish mesothelioma from common morphologic differentials; (4) application of ancillary studies to distinguish benign from malignant mesothelial proliferations, including BAP1 and MTAP immunostains; novel immunomarkers such as Merlin and p53; fluorescence in situ hybridization (FISH) for homozygous deletion of CDKN2A; and novel molecular assays; (5) practical recommendations for routine reporting of mesothelioma, including grading epithelioid mesothelioma and other prognostic parameters; (6) diagnosis of mesothelioma in situ; (7) cytologic diagnosis of mesothelioma, including use of immunostains and molecular assays; and (8) features of nonmalignant peritoneal mesothelial lesions.

Potential mechanisms for lung fibrosis associated with COVID-19 infection

Pulmonary fibrosis is a sequelae of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection that currently lacks effective preventative or therapeutic measures. Post-viral lung fibrosis due to SARS-CoV-2 has been shown to be progressive on selected patients using imaging studies. Persistent infiltration of macrophages and monocytes, a main feature of SARS-CoV-2 pulmonary fibrosis, and long-lived circulating inflammatory monocytes might be driving factors promoting the profibrotic milieu in the lung. The upstream signal(s) that regulates the presence of these immune cells (despite complete viral clearance) remains to be explored. Current data indicate that much of the stimulating signals are localized in the lungs. However, an ongoing low-grade systemic inflammation in long Coronavirus Disease 2019 (COVID-19) symptoms suggests that certain non-pulmonary regulators such as epigenetic changes in hematopoietic stem cells might be critical to the chronic inflammatory response. Since nearly one-third of the world population have been infected, a timely understanding of the underlying pathogenesis leading to tissue remodeling is required. Herein, we review the potential pathogenic mechanisms driving lung fibrosis following SARS-CoV-2 infection based upon available studies and our preliminary findings (Graphical abstract).

Engineered Fibroblast Extracellular Vesicles Attenuate Pulmonary Inflammation and Fibrosis in Bleomycin-Induced Lung Injury

Pulmonary fibrosis is a progressive disease for which no curative treatment exists. We have previously engineered dermal fibroblasts to produce extracellular vesicles with tissue reparative properties dubbed activated specialized tissue effector extracellular vesicles (ASTEX). Here, we investigate the therapeutic utility of ASTEX in vitro and in a mouse model of bleomycin-induced lung injury. RNA sequencing demonstrates that ASTEX are enriched in micro-RNAs (miRs) cargo compared with EVs from untransduced dermal fibroblast EVs (DF-EVs). Treating primary macrophages with ASTEX reduced interleukin (IL)6 expression and increased IL10 expression compared with DF-EV-exposed macrophages. Furthermore, exposure of human lung fibroblasts or vascular endothelial cells to ASTEX reduced expression of smooth muscle actin, a hallmark of myofibroblast differentiation (respectively). In vivo, intratracheal administration of ASTEX in naïve healthy mice demonstrated a favorable safety profile with no changes in body weight, lung weight to body weight, fibrotic burden, or histological score 3 weeks postexposure. In an acute phase (short-term) bleomycin model of lung injury, ASTEX reduced lung weight to body weight, IL6 expression, and circulating monocytes. In a long-term setting, ASTEX improved survival and reduced fibrotic content in lung tissue. These results suggest potential immunomodulatory and antifibrotic properties of ASTEX in lung injury.

Improvement in plasma D-dimer level in severe SARS-CoV-2 infection can be an indicator of fibrinolysis suppression: Case reports

RATIONALE

Fibrinolysis shutdown associated with severe thrombotic complications is a recently recognized syndrome that was previously seldom investigated in patients with severe severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. It presents a unique therapeutic dilemma, as anticoagulation with heparin alone is insufficient to address the imbalance in fibrinolysis. And while the use of fibrinolytic agents could limit the disease severity, it is often associated with bleeding complications. There is a need for biomarkers that will guide the timely stratification of patients into those who may benefit from both anticoagulant and fibrinolytic therapies.

PATIENT CONCERNS

All 3 patients presented with shortness of breath along with comorbidities predisposing them to severe SARS-CoV-2 infection. One patient (Patient 3) also suffered from bilateral deep venous thrombosis.

DIAGNOSES

All 3 patients tested positive for SARS-CoV-2 RNA by reverse transcription polymerase chain reaction (RT-PCR) and were eventually diagnosed with respiratory failure necessitating intubation.

INTERVENTIONS

All 3 patients required mechanical ventilation support, 2 of which also required renal replacement therapy. All 3 patients were also placed on anticoagulation therapy.

OUTCOMES

In Patients 1 and 2, the initial D-dimer levels of 0.97 μg/ml fibrinogen equivalent units (FEU) and 0.83 μg/ml FEU were only slightly elevated (normal <0.50 μg/ml FEU). They developed rising D-dimer levels to a peak of 13.21 μg/ml FEU and >20.0 μg/ml FEU, respectively, which dropped to 1.34 μg/ml FEU 8 days later in Patient 1 and to 2.94 μg/ml on hospital day 13 in Patient 2. In Patient 3, the D-dimer level on admission was found to be elevated to >20.00 μg/ml FEU together with imaging evidence of thrombosis. And although he received therapeutic heparin infusion, he still developed pulmonary embolism (PE) and his D-dimer level declined to 5.91 μg/ml FEU. Despite "improvement" in their D-dimer levels, all 3 patients succumbed to multi-system organ failure. On postmortem examination, numerous arterial and venous thromboses of varying ages, many consisting primarily of fibrin, were identified in the lungs of all patients.

LESSONS

High D-dimer levels, with subsequent downtrend correlating with clinical deterioration, seems to be an indicator of fibrinolysis suppression. These findings can help form a hypothesis, as larger cohorts are necessary to demonstrate their reproducibility.

Comprehensive Molecular and Pathologic Evaluation of Transitional Mesothelioma Assisted by Deep Learning Approach: A Multi-Institutional Study of the International Mesothelioma Panel from the MESOPATH Reference Center

INTRODUCTION

Histologic subtypes of malignant pleural mesothelioma are a major prognostic indicator and decision denominator for all therapeutic strategies. In an ambiguous case, a rare transitional mesothelioma (TM) pattern may be diagnosed by pathologists either as epithelioid mesothelioma (EM), biphasic mesothelioma (BM), or sarcomatoid mesothelioma (SM). This study aimed to better characterize the TM subtype from a histological, immunohistochemical, and molecular standpoint. Deep learning of pathologic slides was applied to this cohort.

METHODS

A random selection of 49 representative digitalized sections from surgical biopsies of TM was reviewed by 16 panelists. We evaluated BAP1 expression and CDKN2A (p16) homozygous deletion. We conducted a comprehensive, integrated, transcriptomic analysis. An unsupervised deep learning algorithm was trained to classify tumors.

RESULTS

The 16 panelists recorded 784 diagnoses on the 49 cases. Even though a Kappa value of 0.42 is moderate, the presence of a TM component was diagnosed in 51%. In 49% of the histological evaluation, the reviewers classified the lesion as EM in 53%, SM in 33%, or BM in 14%. Median survival was 6.7 months. Loss of BAP1 observed in 44% was less frequent in TM than in EM and BM. p16 homozygous deletion was higher in TM (73%), followed by BM (63%) and SM (46%). RNA sequencing unsupervised clustering analysis revealed that TM grouped together and were closer to SM than to EM. Deep learning analysis achieved 94% accuracy for TM identification.

CONCLUSION

These results revealed that the TM pattern should be classified as non-EM or at minimum as a subgroup of the SM type.

Interobserver Variation among Pathologists and Refinement of Criteria in Distinguishing Separate Primary Tumors from Intrapulmonary Metastases in Lung

Multiple tumor nodules are seen with increasing frequency in clinical practice. On the basis of the 2015 WHO classification of lung tumors, we assessed the reproducibility of the comprehensive histologic assessment to distinguish second primary lung cancers (SPLCs) from intrapulmonary metastases (IPMs), looking for the most distinctive histologic features. An international panel of lung pathologists reviewed a scanned sequential cohort of 126 tumors from 48 patients and recorded an agreed set of histologic features, including tumor typing and predominant pattern of adenocarcinoma, thereby opining whether the case was SPLC, IPM, or a combination thereof. Cohen κ statistics of 0.60 on overall assessment of SPLC or IPM indicated a good agreement. Likewise, there was good agreement (κ score 0.64, p < 0.0001) between WHO histologic pattern in individual cases and SPLC or IPM status, but the proportions diversified for histologic pattern and SPLC or IPM status (McNemar test, p < 0.0001). The strongest associations for distinguishing between SPLC and IPM were observed for nuclear pleomorphism, cell size, acinus formation, nucleolar size, mitotic rate, nuclear inclusions, intraalveolar clusters, and necrosis. Conversely, the associations for lymphocytosis, mucin content, lepidic growth, vascular invasion, macrophage response, clear cell change, acute inflammation keratinization, and emperipolesis did not reach significance with tumor extent. Comprehensive histologic assessment is recommended for distinguishing SPLC from IPM with good reproducibility among lung pathologists. In addition to main histologic type and predominant patterns of histologic subtypes, nuclear pleomorphism, cell size, acinus formation, nucleolar size, and mitotic rate strongly correlate with pathologic staging status.

Guidelines for Pathologic Diagnosis of Malignant Mesothelioma 2017 Update of the Consensus Statement From the International Mesothelioma Interest Group

CONTEXT

- Malignant mesothelioma (MM) is an uncommon tumor that can be difficult to diagnose.

OBJECTIVE

- To provide updated, practical guidelines for the pathologic diagnosis of MM.

DATA SOURCES

- Pathologists involved in the International Mesothelioma Interest Group and others with an interest and expertise in the field contributed to this update. Reference material included up-to-date, peer-reviewed publications and textbooks.

CONCLUSIONS

- There was discussion and consensus opinion regarding guidelines for (1) distinguishing benign from malignant mesothelial proliferations (both epithelioid and spindle cell lesions), (2) cytologic diagnosis of MM, (3) recognition of the key histologic features of pleural and peritoneal MM, (4) use of histochemical and immunohistochemical stains in the diagnosis and differential diagnosis of MM, (5) differentiating epithelioid MM from various carcinomas (lung, breast, ovarian, and colonic adenocarcinomas, and squamous cell and renal cell carcinomas), (6) diagnosis of sarcomatoid MM, (7) use of molecular markers in the diagnosis of MM, (8) electron microscopy in the diagnosis of MM, and (9) some caveats and pitfalls in the diagnosis of MM. Immunohistochemical panels are integral to the diagnosis of MM, but the exact makeup of panels employed is dependent on the differential diagnosis and on the antibodies available in a given laboratory. Depending on the morphology, immunohistochemical panels should contain both positive and negative markers for mesothelial differentiation and for lesions considered in the differential diagnosis. Immunohistochemical markers should have either sensitivity or specificity greater than 80% for the lesions in question. Interpretation of positivity generally should take into account the localization of the stain (eg, nuclear versus cytoplasmic) and the percentage of cells staining (>10% is suggested for cytoplasmic and membranous markers). Selected molecular markers are now being used to distinguish benign from malignant mesothelial proliferations. These guidelines are meant to be a practical diagnostic reference for the pathologist; however, some new pathologic predictors of prognosis and response to therapy are also included.

EGFR-mutated lung cancer with T790M-acquired resistance in the brain and histologic transformation in the lung

This case report describes the rare occurrence of a T790M resistance mutation found in a central nervous system (CNS) parenchymal metastasis. A concomitant squamous histology transformation in a lung non-T790M-resistant metastasis is also described. The authors hypothesize that this CNS resistance and histology transformation may have resulted from intermittent use of erlotinib treatment. This case report emphasizes the complexities of using erlotinib in the induction setting.

Pulmonary manifestations of inflammatory bowel disease: case presentations and review

Inflammatory bowel disease (IBD) is associated with a number of extraintestinal manifestations that may involve most organ systems. Extraintestinal manifestations are more common in Crohn disease (CD) and may include rheumatologic, ocular, dermatologic, biliary and pulmonary manifestations. The most common pulmonary manifestations of IBD are drug-induced lung disease. Other manifestations include parenchymal disease, pleuritis and overlap syndromes. We present a case series of 7 patients with non-infectious pulmonary manifestations of IBD, which included cryptogenic organizing pneumonia, usual interstitial pneumonitis (UIP), Langerhan's granulomatosis, and eosinophilic pneumonia. Concurrent extraintestinal manifestations present in these patients included arthralgia, iritis, and pyoderma gangrenosum. In most patients the development of pulmonary disease parallels that of the intestinal disease activity, extraintestinal manifestations and concurrent use of 5-ASA medications.

Evidence-based criteria to help distinguish metastatic breast cancer from primary lung adenocarcinoma on thoracic frozen section

The distinction between primary lung adenocarcinoma and metastatic breast carcinoma in patients with a history of breast cancer is difficult by frozen section (FS) analysis. Our experience with 129 FSs from 121 patients with a pulmonary nodule and a history of breast cancer was reviewed. The pretest odds ratio of primary pulmonary carcinoma/metastatic breast carcinoma was 2.6. The incidence of 12 histopathologic features was assessed in a "training set" composed of 20 FSs, 10 with primary lung adenocarcinoma and 10 with metastatic breast cancer. A differential diagnosis model composed of significant pathologic features that favor the diagnosis of primary lung adenocarcinoma (acini, lepidic growth, nuclear pseudoinclusions, and scar) or metastatic breast carcinoma (comedonecrosis, solid nests, trabecular architecture, and cribriform growth) was identified. The external validity of this model was successfully tested by challenging 19 pathologists and trainees with a test set of 20 unknown FSs, supporting the clinical applicability of the diagnostic model.

Epigenetic silencing of the candidate tumor suppressor gene Per1 in non-small cell lung cancer

PURPOSE

Epigenetic events are a critical factor contributing to cancer development. The purpose of this study was to identify tumor suppressor genes silenced by DNA methylation and histone deacetylation in non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

We used microarray analysis to screen for tumor suppressor genes.

RESULTS

We identified Per1, a core circadian gene, as a candidate tumor suppressor in lung cancer. Although Per1 levels were high in normal lung, its expression was low in a large panel of NSCLC patient samples and cell lines. Forced expression of Per1 in NSCLC cell lines led to significant growth reduction and loss of clonogenic survival. Recent studies showed that epigenetic regulation, particularly histone H3 acetylation, is essential for circadian function. Using bisulfite sequencing and chromatin immunoprecipitation, we found that DNA hypermethylation and histone H3 acetylation are potential mechanisms for silencing Per1 expression NSCLC.

CONCLUSIONS

These results support the hypothesis that disruption of circadian rhythms plays an important role in lung tumorigenesis. Moreover, our findings suggest a novel link between circadian epigenetic regulation and cancer development.

A system for sharing routine surgical pathology specimens across institutions: the Shared Pathology Informatics Network

This report presents an overview for pathologists of the development and potential applications of a novel Web enabled system allowing indexing and retrieval of pathology specimens across multiple institutions. The system was developed through the National Cancer Institute's Shared Pathology Informatics Network program with the goal of creating a prototype system to find existing pathology specimens derived from routine surgical and autopsy procedures ("paraffin blocks") that may be relevant to cancer research. To reach this goal, a number of challenges needed to be met. A central aspect was the development of an informatics system that supported Web-based searching while retaining local control of data. Additional aspects included the development of an eXtensible Markup Language schema, representation of tissue specimen annotation, methods for deidentifying pathology reports, tools for autocoding critical data from these reports using the Unified Medical Language System, and hierarchies of confidentiality and consent that met or exceeded federal requirements. The prototype system supported Web-based querying of millions of pathology reports from 6 participating institutions across the country in a matter of seconds to minutes and the ability of bona fide researchers to identify and potentially to request specific paraffin blocks from the participating institutions. With the addition of associated clinical and outcome information, this system could vastly expand the pool of annotated tissues available for cancer research as well as other diseases.

Adenovirus mediated IL-10 gene transfer to the airway of the rat lung for prevention of lung allograft rejection

BACKGROUND

The ability to express genes with potential immunoregulatory capacity could reduce allograft rejection (AR). We examined the feasibility of transferring the viral interleukin-10 (vIL-10) gene into rat lungs by intra-bronchial instillation and the subsequent effects of delivered vIL-10 on acute lung AR.

METHODS

First, the adenoviral beta-galactosidase vector (adv-beta-gal) particles were instilled into the airway of the rat lung and protein synthesis of beta-gal was examined by histochemical staining. Next, the ability of the adenoviral vIL-10 vector (adv-vIL-10) transfection to modify AR was examined in a highly histoincompatible rat lung transplant model (BN-->Lew). Donor left lungs were transfected with 3 x 10(8) pfu/0.3 mL of adv-vIL-10 (vIL-10 group) or adv-beta-gal (control group) 3 days before transplantation. On day 6 post-transplant, lung allografts were harvested and AR was graded histologically (stage 0-4). Several pathological categories of inflammation (perivascular, peribronchial, or peribronchiolar mononuclear infiltrates, edema, vasculitis, intraalveolar hemorrhage, and necrosis) were also examined and scored on a scale of 0-4 as previously described.

RESULTS

A successful transgene protein synthesis by adv-beta-gal in alveolar epithelial cells and alveolar macrophages was confirmed by histochemical staining with X-gal. The vIL-10 group showed a trend toward an improved stage of AR (3.75 +/- 0.5 vs. 4.0 +/- 0), and also a decreased pathological scores for edema (3.5 +/- 0.6 vs. 4.0 +/- 0), intraalveolar hemorrhage (2.3 +/- 1.0 vs. 2.5 +/- 0.6) and necrosis (1.5 +/- 0.5 vs. 1.75 +/- 1.3) compared with the control group, however, the differences in any pathological scores between the two groups did not reach a statistical significance.

CONCLUSIONS

1. A successful transgene protein synthesis in alveolar epithelial cells was ensured by intra-bronchial instillation of an adenoviral vector encoding beta-galactosidase gene. 2. Transferring the vIL-10 gene into rat lungs by intra-bronchial instillation did not seem to reduce lung AR significantly, as opposed to the results of our previous experiments in a rat cardiac allograft model. This discrepancy may be explained by several potential factors including the immunogenecity of adenoviral vectors in conjunction with the nature of the lung more susceptible to immune response and inflammation.

Suppression of Cell Proliferation and Signaling Transduction by Connective Tissue Growth Factor in Non–Small Cell Lung Cancer Cells

Connective tissue growth factor (CTGF) is a secreted protein that belongs to CCN family. The proteins in this family are implicated in various biological processes, such as angiogenesis, adhesion, migration, and apoptosis. In this study, we explored the roles of CTGF in lung tumorigenesis. The expression levels of CTGF in 58 lung cancer samples were reduced by >2 fold in 57% of the samples compared with matched normal samples using real-time reverse transcription-PCR. These results were confirmed by immunohistochemical staining for CTGF in normal lung epithelia and lung cancer. Cellular proliferation was inhibited in non-small cell lung cancer (NSCLC) cell lines NCI-H460, NCI-H520, NCI-H1299, and SK-MES-1 by CTGF overexpression. Partially purified CTGF suppressed lung cancer cell growth. The growth inhibition caused by CTGF overexpression was associated with growth arrest at G(0)-G(1) and prominent induction of p53 and ADP ribosylation factor. Most interestingly, overexpression of CTGF suppressed insulin-like growth factor-I-dependent Akt phosphorylation and epidermal growth factor-dependent extracellular signal-regulated kinase 1/2 phosphorylation. In summary, NSCLC cells expressed decreased levels of CTGF compared with normal lung cells; this lower expression has an effect on lung cancer cell proliferation and its cellular response to growth factors. Our data suggest that CTGF may behave as a secreted tumor suppressor protein in the normal lung, and its expression is suppressed in many NSCLCs.

Chloroquine-induced cardiomyopathy-echocardiographic features

A 61-year-old woman with a 30-year history of systemic lupus erythematosus treated with chloroquine sulfate presented with complete heart block, congestive heart failure, and findings of restrictive cardiomyopathy on echocardiogram. Thickening of mitral, aortic, and tricuspid valves along with mild to moderate valve regurgitation was also present. Magnetic resonance imaging showed increased gadolinium uptake in the interventricular septum and the left ventricular lateral wall. Endomyocardial biopsy specimen showed marked myocardial cytoplasmic vacuolation and extensive myelin figures. Seven months after discontinuation of chloroquine, she showed significant clinical improvement and reversal of cardiomyopathy on echocardiography. This is the first case report describing a cardiomyopathy with prolonged use of chloroquine involving the conduction system, cardiac valves, and the myocardium with reversal on discontinuation of the drug.

Migration of wooden skewer foreign bodies from the gastrointestinal tract in eight dogs

Wooden skewer foreign bodies were found in eight dogs. Five presented for evaluation of draining sinuses and two for inflammatory disease referrable to the thorax, abdomen or pelvic region. In an additional case, pneumothorax resulted from perforation of the stomach and diaphragm. Ingestion was considered the most likely mode of access of the foreign body in all cases. Although the wooden foreign bodies were seen radiographically in only two dogs, identification of soft tissue or bony changes, or the results of contrast sinography assisted diagnosis. Surgical retrieval led to resolution of signs in all cases.

Neural networks as a prognostic tool of surgical risk in lung resections

BACKGROUND

Assessment of surgical risk in patients undergoing pulmonary resection is a fundamental goal for thoracic surgeons. Usually used risk indices do not predict the individual outcome. Neural networks (NN) are artificial intelligence software models that have been used for estimation of several prognostic situations.

METHODS

Ninety-six clinical and laboratory features from each one of 141 patients who underwent lung resection were retrospectively collected. The variables were used as input data for the software. Cases were divided into a training set (n = 113) and a test set (n = 28). Four NN models were trained using the data from the training set: (1) using all variables; (2) using only the Goldman and Torrington scores; (3) using all variables except for the two scores. A fourth NN was programmed with all variables to estimate the development of major postoperative complications. The trained NN models were tested with the test set data.

RESULTS

The NN using all variables with or without the scores were able to correctly classify all 28 test cases against actual outcome. The NN using all variables also estimated major postoperative complications correctly in all 28 test cases. The NN using only two indices (Goldman and Torrington) yielded 6 of 28 errors in classification.

CONCLUSIONS

These data suggest that NN can integrate results from multiple data predicting the individual outcome for patients, rather than assigning them to less-precise risk group categories.

Hydrophobic extracts of a Chinese herb (CMX-13) exhibit potent immunosuppressive properties and prevent acute rejection in a highly histoincompatible model of rat lung transplantation

BACKGROUND

The potential of higher plants as sources for new immunosuppressive medications is well recognized. In our experiments we investigated the immunosuppressive effect of a highly refined and potent extract of a Chinese herbal preparation, CMX-13, on inhibiting acute allograft rejection (AR) in a highly histoincompatible rat lung transplant model, BN-->LEW, and on lymphocyte activation and cytokine gene expression in vitro.

METHODS

Left lung transplants: the control group (group 1) received only dimethylsulfoxide (DMSO) which is the solvent for CMX-13. Group 2 received intramuscular cyclosporin A (CsA, 25 mg/kg) on day 2 posttransplant. Group 3 and 4 received i.p. CMX-13 (0.5 mg/day, low dose and 5 mg/day, high dose, respectively) on day 1, 2, and 3 posttransplant. All animals were killed on day 6 posttransplant. Several pathological categories of inflammation were examined. In vitro experiments: rat spleen cells were incubated with Con A or irradiated stimulator cells with/without serial dilutions of CMX-13 or CsA. Cell proliferation was measured by 3H-thymidine incorporation. mRNA expression of interleukin-2 and interferon-gamma was examined by reverse transcriptase-polymerase chain reaction.

RESULTS

The severity of AR in animals receiving high dose CMX-13 was significantly reduced (stage II, P<0.05) compared with controls (stage IV). Significant differences were also seen when more specific parameters of inflammation were examined (necrosis, 0 vs. 1.7+/-1.0, P<0.05; interalveolar hemorrhage, 0 vs. 3.0+/-0.9, P<0.05). The responses seen in the animals treated with high dose CMX-13 were similar to those in the CsA group. CMX-13 inhibited T cell proliferative responses induced by Con A and alloantigen stimulation in a dose-dependent manner that were similar to CsA. Interleukin-2, and interferon-gamma mRNA expression in Con A-stimulated spleen cells was not inhibited by CMX-13 although CsA showed significant inhibition.

CONCLUSIONS

1) CMX-13 significantly reduces the stage of AR and parameters of inflammation in a highly histoincompatible rat lung transplant model. 2) CMX-13 has equal potency to CsA in the inhibition of Con A and alloantigen stimulated rat spleen cell proliferation. 3) CMX-13 showed no inhibitory effects on IL-2 and gamma-IFN mRNA expression, suggesting that its mechanism of action is different from CsA. 4) CMX-13 or derivatives may have potential utility as an immunosuppressive agent(s) in modulation of AR and management of other inflammatory and immunological disorders.

Partial molar transformation of the placenta of presumably monozygotic twins

A pregnancy with one normal female fetus and a placenta that was divided into halves, one normal the other molar, is described. Genetic analysis shows the molar component to be hyperdiploid/tetraploid but having an identical DNA composition as the normal twin. Because there was no trophoblastic proliferation and the hyperdiploid cells were confined to the villous stroma, and because the molar component was still being perfused by diploid vessels from the normal twin, we believe the mole is derived from polyploidization of the mesenchymal epiblast in a monozygotic twin pregnancy.

Prototype Web-based continuing medical education using FlashPix images

Continuing Medical Education (CME) is a requirement among practicing physicians to promote continuous enhancement of clinical knowledge to reflect new developments in medical care. Previous research has harnessed the Web to disseminate complete pathology CME case studies including history, images, diagnoses, and discussions to the medical community. Users submit real-time diagnoses and receive instantaneous feedback, eliminating the need for hard copies of case material and case evaluation forms. This project extends the Web-based CME paradigm with the incorporation of multi-resolution FlashPix images and an intuitive, interactive user interface. The FlashPix file format combines a high-resolution version of an image with a hierarchy of several lower resolution copies, providing real-time magnification via a single image file. The Web interface was designed specifically to simulate microscopic analysis, using the latest Javascript, Java and Common Gateway Interface tools. As the project progresses to the evaluation stage, it is hoped that this active learning format will provide a practical and efficacious environment for continuing medical education with additional application potential in classroom demonstrations, proficiency testing, and telepathology. Using Microsoft Internet Explorer 4.0 and above, the working prototype Web-based CME environment is accessible at http://telepathology.upmc.edu/WebInterface/NewInterface/welcome.html.

Prolongation of skin allograft survival is associated with reduced Th1 cytokine responses in the WKY-->F344 rat model

BACKGROUND

We have reported previously that F344 rats develop a spontaneous tolerance to WKY lung allografts and show long-term retention of donor-specific skin grafts placed 35 days after lung transplantation. In this study, we investigated the immunologic mechanisms that may be responsible for the prolonged skin graft survival in animals tolerized with lung allografts.

METHODS

In the rejection group, WKY skin grafts were placed on normal F344 rats, whereas, in the tolerance group, the skin grafts were placed on F344 rats that had received a WKY lung transplant 35 days before skin grafting. Th1 (interleukin [IL]-2 and interferon-gamma [IFN-gamma]) and Th2 (IL-4 and IL-10) cytokine as well as transforming growth factor-beta1 mRNA expression in skin grafts and in draining lymph nodes were determined by reverse transcription-polymerase chain reaction. Macrophage and lymphocyte infiltration in skin grafts and the number of Langerhans cells in epidermal sheets of the grafts were examined by immunohistochemistry.

RESULTS

IL-2 and IFN-gamma mRNA expression was significantly decreased in both the skin grafts and the draining lymph nodes of the tolerance group, compared to the rejection group, whereas IL-10 and transforming growth factor-beta1 mRNA expression was similar in both groups and IL-4 mRNA was rarely detected. Decreased and delayed CD8+, macrophage, and natural killer cell infiltration in the skin grafts from the tolerance group was also detected. Similar reduction in the number of Langerhans cells in the epidermis of the grafts from both groups was seen on day 1 after skin grafting, and thereafter the number remained stable in both groups.

CONCLUSIONS

Reduced expression of Th1 cytokines and decreased infiltration of CD8+ cells, macrophages, and natural killer cells in the skin grafts may be responsible for prolongation of skin graft survival in the tolerance group.

Estimation of tumor stage and lymph node status in patients with colorectal adenocarcinoma using probabilistic neural networks and logistic regression

Staging colorectal adenocarcinoma on the basis of biopsy specimens could identify patients who might benefit from neoadjuvant therapy without undergoing resection first. In this study, we evaluated the ability of artificial neural networks with genetic algorithms and multivariate logistic regression to predict the stage of 99 patients with primary colorectal adenocarcinoma by analyzing age, tumor grade, and immunoreactivity to p53 and bcl-2 with use of endoscopically obtained biopsy specimens. We correlated results with regional lymph node status and tumor stage, identified in subsequent colectomy specimens. bcl-2 and p53 protein expression were demonstrated by immunohistochemical methods, using formalin-fixed, paraffin-embedded biopsy tissues. Tumor grade was evaluated in hematoxylinand eosin-stained sections. Patients were divided into training (n = 75) and testing cases (n = 24). Several probabilistic neural networks with genetic algorithm models were trained, using the four prognostic features as input neurons and regional lymph node status or stage as output neurons. Data were analyzed with univariate statistics and multivariate logistic regression. The cases were divided into training (n = 40) and testing (n = 59). The best two models classified correctly the lymph node status of 20 of 24 test patients (specificity, 80%; sensitivity, 85%; positive predictive value, 86%) and the tumor stage of 21 of 24 test patients (specificity, 82%; sensitivity, 92%; positive predictive value, 85%), respectively. Tumor grade and p53 protein were statistically significant (P < .05) by analysis of variance for lymph node status and tumor stage. Logistic regression models with these two independent variables correctly estimated the probability of lymph node metastases in 44 of 59 test cases and the tumor stage of 43 of 59 test cases, respectively. Results indicated the usefulness of probabilistic neural networks in the population studied, but the findings should be validated with large groups of patients.

"Refractoriness" of airflow obstruction associated with isolated lymphocytic bronchiolitis/bronchitis in pulmonary allografts

The clinical significance of an isolated "lymphocytic bronchiolitis/bronchitis" (grade B) as detected in transbronchoscopic biopsy specimens (TBB) is unclear. We therefore have reviewed the spirometric responses associated with isolated grade B diagnoses and contrasted them with episodes of "acute cellular rejection" (grade A); the latter are manifested by "perivascular lymphocytic infiltration." Because lymphocytic bronchiolitis/ bronchitis is considered a nonspecific histologic pattern that may be observed with either allograft rejection or respiratory infections, episodes were analyzed with respect to the presence (grade B [+] CMV) or absence (grade B [-] CMV) of cytomegalovirus infection. The maximum forced expiratory volume in 1 second (FEV1) during the preceding 3 months was used as a baseline for computing percent change in FEV1 coincident with transbronchoscopic biopsies (delta %FEV1 PRE) and maximum values obtained during the 3 months subsequent to specific therapies (delta %FEV1 POST). All episodes of acute cellular rejection (grades A1 to 4) and symptomatic lymphocytic bronchiolitis/bronchitis (grade B) were treated with "pulsed-dose" methylprednisolone, whereas intravenous ganciclovir was administered to patients at risk for recrudescence of cytomegalovirus. Between March 1, 1989, and September 1, 1995, 366 TBB procedures were performed for clinical indications in 57 lung transplant recipients. Histologic diagnoses with acceptable serial spirometric values included grade A1 (n = 9), grade A2 (n = 27), grade A3 (n = 2), grade B(-)CMV (n = 25) and grade B(+)CMV (n = 9). The delta %FEV1 PRE coincident with TBB were not statistically different for the different histologic groups. For grade A1, delta %FEV1 PRE was -14.6% +/- 5.2% (X +/- SEM); A2, -7.6% +/- 1.8%; B(-)CMV, -14.8% +/- 3.9%; and B(+)CMV, -14.8% +/- 2.3%. After treatment, the delta %FEV1 POST, relative to baseline values, were for grade A1, -8.8% +/- 7.1%, A2, +0.26% +/- 2.6%; B(-)CMV, -12.0% +/- 3.8%; and B(+)CMV, -6.2% +/- 2.8%. The delta %FEV1 POST values after pulsed methylprednisolone were significantly greater for histologic grade A2 than grade B(-)CMV (unpaired Student's t test, P < 0.01; 95% confidence interval for the difference of means: 3.34% to 21.2%). Grade A2 rejection was associated with spirometric improvement to within 10% of baseline values in 52% of episodes; whereas with grade B(-)CMV, this salutary response was observed in only 32% of episodes. Bronchiolitis obliterans syndrome stage 1b developed in 13 of 20 (65%) recipients, approximately 7.9 +/- 3.4 months after detection of histologic grade B and 21.2 +/- 9.5 months after transplantation. We conclude that the relative "refractoriness" of histologic grade B most likely reflects a continuum of bronchiolitis obliterans after lung transplantation and, hence, may warrant different immunosuppressive strategies. Furthermore, spirometric decrement associated with acute cellular rejection (grade A) may be ameliorated, but often not completely reversed, after pulsed methylprednisolone. We speculate that surveillance TBB may prove rewarding by enabling an earlier detection of these histologic diagnoses before the development of physiologic impairment.

Upper airway obstruction secondary to acinic cell carcinoma of the trachea. Use of Nd:YAG laser

Comprising 1 to 4% of all tumors and 7 to 15% of malignant neoplasms of the major salivary glands, acinic cell carcinoma (ACC) rarely occurs in the respiratory tract. There has been only one case of ACC of the trachea previously reported in the medical literature. A second case of ACC of the trachea associated with upper airway obstruction and its management by Nd: YAG laser and surgical resection is reported.

Quality assurance issues in DNA image cytometry

DNA image cytometry is currently used in many clinical laboratories as a prognostic tool for the study of patients with malignant neoplasms. However, quality assurance (QA) procedures for image cytometry (IC) have not been standardized. National proficiency testing programs for DNA IC are yet to be developed. We describe our QA program for DNA IC. Indicators of quality; thresholds for evaluation; methods for collection, organization, and evaluation of data; and actions recommended to deal with problems are described for each of the phases of DNA IC. They include QA procedures for sample acceptability; staining technique; instrumentation, including linearity and calibration verification; and correlation with other cytometric methods. The difficult problem of standardizing the postanalytical phase of QA is discussed. The need for a consensus conference to adopt standardized QA procedures for DNA image analysis is emphasized.

Revision of the 1990 working formulation for the classification of pulmonary allograft rejection: Lung Rejection Study Group

In 1990, an international grading scheme for the grading of pulmonary allograft rejection was instituted. The use of this classification has resulted in a uniformity of grading which has allowed inter-institutional collaborations and communication unique in allograft monitoring. In 1995 an expanded group of international pathologists convened and revised the original proposal. This article summarizes the updated classification for pulmonary allograft rejection. In brief, acute rejection is based on perivascular and interstitial mononuclear infiltrates. Each grade of acute rejection should mention the presence of coexistent airway inflammation, the intensity of which may also be graded. Chronic rejection is divided into bronchiolitis obliterans--active or inactive--and vascular atherosclerosis--accelerated arterial or venous sclerosis.

Assessment of pathological changes associated with chronic allograft rejection and tolerance in two experimental models of rat lung transplantation

Lung transplantation is now routinely performed for a wide range of end-stage cardiopulmonary disorders. Despite overcoming the problems associated with early acute rejection, chronic rejection (CR) in the form of obliterative bronchiolitis has emerged as the primary cause of late graft loss. The mechanisms involved in the development of CR of lung allografts are poorly understood, and no effective therapy is currently available. To better understand the pathological events associated with CR and tolerance, we examined two models of lung allograft rejection established in our laboratory. First, we exchanged left lung allografts between moderately histoincompatible inbred rat strains (WKY-->F344: n = 42 and F344-->WKY: n = 40). The WKY-->F344 model was previously shown to develop spontaneous tolerance, while the converse model (F344-->WKY) showed persistent acute rejection. The purpose of this investigation was to assess histopathological changes associated with long-term grafts left in place up to 140 days after transplant. To confirm that tolerance had developed, skin-grafting experiments were performed. Five skin grafts from each strain were placed on lung allograft recipients on day 35 after transplant and skin allograft survival was assessed and compared with controls. Acute rejection (AR) was graded histologically (stage O-IV) and the pathologic intensity of inflammation and CR were graded (0-4: 0 = 0%, 1 = 1-25%, 2 = 26-50%, 3 = 51-75%, and 4 = 76-100%) on percentage of involvement with the following categories being examined: (a) lymphocytic infiltration (perivascular, peribronchial, and peribronchiolar) and (b) vasculitis, edema, hemorrhage, and necrosis. Finally, chronic rejection was diagnosed by the presence of intimal hyperplasia, interstitial fibrosis, peribronchiolar fibrosis, bronchiolitis obliterans, and bronchiectasis. The WKY-->F344 animals showed progressive AR (stage III, day 21). Thereafter, the AR subsided spontaneously and was stage 0 on day 140. There were no signs of CR in these animals. In the F344-->WKY model, the AR progressed up to stage III-IV (day 21) and maintained for several weeks at stage III. Thereafter, pictures of the lungs showed CR on days 49, 70, and 98. There were significant differences between the two models during the chronic phase, such as interstitial fibrosis (0 +/- 0 vs. 1.8 +/- 1.3, P < 0.005), peribronchiolar fibrosis (0 +/- 0 vs. 3.6 +/- 0.55, P < 0.01), vasculitis (0.2 +/- 0.45 vs. 2.0 +/- 0, P < 0.008), and intimal hyperplasia (0.2 +/- 0.45 vs. 2.6 +/- 0.9, P < 0.008).(ABSTRACT TRUNCATED AT 250 WORDS)

Soluble CTLA4Ig modifies parameters of acute inflammation in rat lung allograft rejection without altering lymphocytic infiltration or transcription of key cytokines

The efficacy of CTLA4Ig in blocking immune activation and allograft rejection (AR) was tested in an aggressive and rapid model of rat lung AR (Brown Norway [BN]-->Lewis [LEW]). CTLA4Ig is a recombinant soluble protein that binds with high affinity to rat B7/BB1 and other surface molecules on APCs, subsequently blocking the binding of B7/BB1 to CD28/CTLA4 on T cells. This interrupts the costimulatory pathway critical for complete T cell activation and completion of the AR process. Left single-lung transplants were performed between BN-->Lew. Five allograft recipients were examined in each group. At transplantation, animals received 250 micrograms of CTLA4Ig or 250 micrograms of control Ig intraperitoneally daily until sacrifice. Animals were sacrificed on days 2, 4, and 7 after transplant. Control (BN-->Lew) grafts show irreversible rejection by day 7. Syngeneic (Lew-->Lew) grafts show no AR on day 7. AR episodes were graded histologically (stages 0-IV) and pathologic intensity of inflammation was graded on percentage of involvement. Cytokine transcript levels were measured in control and CTLA4Ig-treated animals (n = 5 in each group) on day 7 using reverse transcriptase polymerase chain reaction techniques. The most profound differences were found on day 7 after transplant. The degree of lymphocytic infiltration was greater in the CTLA4Ig group (perivascular: 4 +/- 0 vs. 2.6 +/- 0.6, peribronchial: 4 +/- 0 vs. 2.2 +/- 0.4, and peribronchiolar: 3.6 +/- 0.5 vs. 2 +/- 0.3, P < 0.01). However, in striking contrast, the stage of AR (3 +/- 0 vs. 4 +/- 0, P < 0.01), vasculitis (1 +/- 0.7 vs. 2.6 +/- 0.6, P < 0.05), hemorrhage (0.4 +/- 0.6 vs. 3.2 +/- 0.4, P < 0.01), and necrosis (0 +/- 0 vs. 2.4 +/- 0.5, P < 0.005) were significantly reduced in animals treated with CTLA4Ig. Since CTLA4Ig blocks Th1 cell activation in vitro, we compared the levels of Th1 inflammatory cytokines IL-2, gamma-IFN, and TNF-alpha in the two models. The intragraft ratios (CTLA4Ig/control) were IL-2:0.77, gamma-IFN: 1.29, and TNF-alpha:1.33. Thus, CTLA4Ig did not significantly block intragraft production of Th1 cytokines on day 7.(ABSTRACT TRUNCATED AT 400 WORDS)

Neural networks as an aid in the diagnosis of lymphocyte-rich effusions

Neural network (NN) technology was applied to digital image analysis data for 112 Papanicolaou-fixed and -stained smears of lymphocyte-rich effusions (LREs). The smears were analyzed with an inexpensive image analysis system assembled in our laboratory. Several models were developed using backpropagation NN development software in an effort to optimize classification of the LREs as reactive lymphocytosis or malignant lymphoma and to analyze the effects of various parameters on classification rates. The greatest specificity and sensitivity of LRE classification were achieved with NN models that consisted of 7 input neurons, including 5 morphometric and 2 densitometric variables, 10 hidden-layer neurons and 1 output neuron. This NN architecture with a sigmoidal transfer function provided a true cross-validation rate of 89.3% of testing data, with a sensitivity of 76.9%, specificity of 93.0% and shrinkage of 10.7%. The same NN architecture with a step transfer function provided a true cross-validation rate of 95.3%, sensitivity of 85.7%, specificity of 97.6% and shrinkage of 0%. The effects of various parameters, such as network size, shrinkage and ratio of sample size to input layer size, on NN accuracy are discussed.

Differential soluble interleukin-2R levels in bilateral bronchoalveolar lavage after single lung transplantation

Preliminary reports suggest that measurement of the soluble 55 kd subunit of the interleukin-2 receptor may facilitate the diagnosis of allograft rejection in solid organ transplants. Levels of soluble interleukin-2 receptor in serum or plasma have previously lacked sufficient sensitivity and specificity for the diagnosis of acute allograft rejection. Because single lung transplantation is preferentially performed for nonseptic end-stage pulmonary and cardiopulmonary maladies, we questioned whether the pattern of soluble interleukin-2 receptor recovery in bronchoalveolar lavage fluid obtained from both the native and transplanted lungs may enhance correct diagnosis. Fifty-three consecutive fiberoptic bronchoscopic procedures were performed with bilateral bronchoalveolar lavage fluid. Transbronchoscopic biopsies were histologically classified by the International Society for Heart Transplantation Working Formulation for Standardized Nomenclature. "Soluble interleukin-2 receptor index" was calculated as the quotient of soluble interleukin-2 receptor (in units per milliliter) by enzyme-linked immunosorbent assay, divided by protein (in milligrams per milliliter) to correct for differences in bronchoalveolar lavage fluid techniques and cellularity. Soluble interleukin-2 receptor indexes were significantly increased in the allograft bronchoalveolar lavage fluid during histologic grade A (acute rejection) versus normal transbronchoscopic biopsy specimens (3395 +/- 1298 U/mg versus 76 +/- 21 U/mg) associated with an increased transplanted/native lung ratio (69.9 +/- 46 versus 2 +/- 1 [mean +/- standard error of the mean]) (one-way analysis of variance, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of Epstein-Barr virus by polymerase chain reaction in transbronchial biopsies of lung transplant recipients: evidence of infection?

Thirty-nine paraffin-embedded transbronchial biopsies from ten lung transplant recipients were evaluated by the polymerase chain reaction for the presence of Epstein-Barr virus (EBV). Six of these patients had positive EBV serology. Nine biopsies from nine non-transplant patients with nonspecific interstitial pneumonitis were studied as a control group. Eight biopsies from four of the ten transplant patients (40%) were positive for EBV by polymerase chain reaction, utilizing 40 cycles and two sets of primers (501/502) complementary to sequences within the Bam H1 W region of the viral genome. Five of these eight positive biopsies had been diagnosed as mild acute cellular rejection based on clinicopathologic criteria. Three of the four EBV-positive patients showed clinical improvement with antiviral agents prescribed for concomitant cytomegalovirus infection. Our data demonstrate the potential of polymerase chain reaction to detect small quantities of EBV in transbronchial biopsies from lung transplant recipients. Such findings should be interpreted cautiously in the evaluation of lung transplant recipients, since EBV can be detected in the absence of a lymphoproliferative disorder or an active pneumonitis caused by this virus.