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Although postoperative bacterial infections can trigger rejection of pulmonary allografts, the impact of bacterial colonization of donor grafts on alloimmune responses to transplanted lungs remains unknown. Here, we tested the hypothesis that bacterial products present within donor grafts at the time of implantation promote lung allograft rejection. Administration of the toll-like receptor 2 (TLR2) agonist Pam3 Cys4 to Balb/c wild-type grafts triggered acute cellular rejection after transplantation into B6 wild-type recipients that received perioperative costimulatory blockade. Pam3 Cys4 -triggered rejection was associated with an expansion of CD8+ T lymphocytes and CD11c+ CD11bhi MHC (major histocompatibility complex) class II+ antigen-presenting cells within the transplanted lungs. Rejection was prevented when lungs were transplanted into TLR2-deficient recipients but not when MyD88-deficient donors were used. Adoptive transfer of B6 wild-type monocytes, but not T cells, following transplantation into B6 TLR2-deficient recipients restored the ability of Pam3 Cys4 to trigger acute cellular rejection. Thus, we have demonstrated that activation of TLR2 by a bacterial lipopeptide within the donor airways prevents the induction of lung allograft tolerance through a process mediated by recipient-derived monocytes. Our work suggests that donor lungs harboring bacteria may precipitate an inflammatory response that can facilitate allograft rejection.

Although animal models have been evaluated for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, none have fully recapitulated the lung disease phenotypes seen in humans who have been hospitalized. Here, we evaluate transgenic mice expressing the human angiotensin I-converting enzyme 2 (ACE2) receptor driven by the cytokeratin-18 (K18) gene promoter (K18-hACE2) as a model of SARS-CoV-2 infection. Intranasal inoculation of SARS-CoV-2 in K18-hACE2 mice results in high levels of viral infection in lungs, with spread to other organs. A decline in pulmonary function occurs 4 days after peak viral titer and correlates with infiltration of monocytes, neutrophils and activated T cells. SARS-CoV-2-infected lung tissues show a massively upregulated innate immune response with signatures of nuclear factor-κB-dependent, type I and II interferon signaling, and leukocyte activation pathways. Thus, the K18-hACE2 model of SARS-CoV-2 infection shares many features of severe COVID-19 infection and can be used to define the basis of lung disease and test immune and antiviral-based countermeasures.

Antibody-mediated rejection (AMR) is a principal cause of acute and chronic failure of lung allografts. However, mechanisms mediating this oftentimes fatal complication are poorly understood. Here, we show that Foxp3+ T cells formed aggregates in rejection-free human lung grafts and accumulated within induced bronchus-associated lymphoid tissue (BALT) of tolerant mouse lungs. Using a retransplantation model, we show that selective depletion of graft-resident Foxp3+ T lymphocytes resulted in the generation of donor-specific antibodies (DSA) and AMR, which was associated with complement deposition and destruction of airway epithelium. AMR was dependent on graft infiltration by B and T cells. Depletion of graft-resident Foxp3+ T lymphocytes resulted in prolonged interactions between B and CD4+ T cells within transplanted lungs, which was dependent on CXCR5-CXCL13. Blockade of CXCL13 as well as inhibition of the CD40 ligand and the ICOS ligand suppressed DSA production and prevented AMR. Thus, we have shown that regulatory Foxp3+ T cells residing within BALT of tolerant pulmonary allografts function to suppress B cell activation, a finding that challenges the prevailing view that regulation of humoral responses occurs peripherally. As pulmonary AMR is largely refractory to current immunosuppression, our findings provide a platform for developing therapies that target local immune responses.

Although animal models have been evaluated for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, none have fully recapitulated the lung disease phenotypes seen in humans who have been hospitalized. Here, we evaluate transgenic mice expressing the human angiotensin I-converting enzyme 2 (ACE2) receptor driven by the cytokeratin-18 (K18) gene promoter (K18-hACE2) as a model of SARS-CoV-2 infection. Intranasal inoculation of SARS-CoV-2 in K18-hACE2 mice results in high levels of viral infection in lungs, with spread to other organs. A decline in pulmonary function occurs 4 days after peak viral titer and correlates with infiltration of monocytes, neutrophils and activated T cells. SARS-CoV-2-infected lung tissues show a massively upregulated innate immune response with signatures of nuclear factor-κB-dependent, type I and II interferon signaling, and leukocyte activation pathways. Thus, the K18-hACE2 model of SARS-CoV-2 infection shares many features of severe COVID-19 infection and can be used to define the basis of lung disease and test immune and antiviral-based countermeasures.

Severe Acute Respiratory Syndrome Coronavirus -2 (SARS-CoV-2) emerged in late 2019 and has spread worldwide resulting in the Coronavirus Disease 2019 (COVID-19) pandemic. Although animal models have been evaluated for SARS-CoV-2 infection, none have recapitulated the severe lung disease phenotypes seen in hospitalized human cases. Here, we evaluate heterozygous transgenic mice expressing the human ACE2 receptor driven by the epithelial cell cytokeratin-18 gene promoter (K18-hACE2) as a model of SARS-CoV-2 infection. Intranasal inoculation of SARS-CoV-2 in K18-hACE2 mice results in high levels of viral infection in lung tissues with additional spread to other organs. Remarkably, a decline in pulmonary function, as measured by static and dynamic tests of respiratory capacity, occurs 4 days after peak viral titer and correlates with an inflammatory response marked by infiltration into the lung of monocytes, neutrophils, and activated T cells resulting in pneumonia. Cytokine profiling and RNA sequencing analysis of SARS-CoV-2-infected lung tissues show a massively upregulated innate immune response with prominent signatures of NF-kB-dependent, type I and II interferon signaling, and leukocyte activation pathways. Thus, the K18-hACE2 model of SARS-CoV-2 infection recapitulates many features of severe COVID-19 infection in humans and can be used to define the mechanistic basis of lung disease and test immune and antiviral-based countermeasures.

Tertiary lymphoid organs are aggregates of immune and stromal cells including high endothelial venules and lymphatic vessels that resemble secondary lymphoid organs and can be induced at nonlymphoid sites during inflammation. The function of lymphatic vessels within tertiary lymphoid organs remains poorly understood. During lung transplant tolerance, Foxp3(+) cells accumulate in tertiary lymphoid organs that are induced within the pulmonary grafts and are critical for the local downregulation of alloimmune responses. Here, we showed that tolerant lung allografts could induce and maintain tolerance of heterotopic donor-matched hearts through pathways that were dependent on the continued presence of the transplanted lung. Using lung retransplantation, we showed that Foxp3(+) cells egressed from tolerant lung allografts via lymphatics and were recruited into donor-matched heart allografts. Indeed, survival of the heart allografts was dependent on lymphatic drainage from the tolerant lung allograft to the periphery. Thus, our work indicates that cellular trafficking from tertiary lymphoid organs regulates immune responses in the periphery. We propose that these findings have important implications for a variety of disease processes that are associated with the induction of tertiary lymphoid organs.

Antibody-mediated rejection (AMR) is an increasingly recognized form of lung rejection. C4d deposition has been an inconsistent finding in previous reports and its role in the diagnosis has been controversial. We conducted a retrospective single-center study to characterize cases of C4d-negative probable AMR and to compare these to cases of definite (C4d-positive) AMR. We identified 73 cases of AMR: 28 (38%) were C4d-positive and 45 (62%) were C4d-negative. The two groups had a similar clinical presentation, and although more patients in the C4d-positive group had neutrophilic capillaritis (54% vs. 29%, p = 0.035), there was no significant difference in the presence of other histologic findings. In spite of aggressive antibody-depleting therapy, 19 of 73 (26%) patients in the overall cohort died within 30 days, but there was no significant difference in freedom from chronic lung allograft dysfunction (CLAD) or survival between the two groups. We conclude that AMR may cause allograft failure, but the diagnosis requires a multidisciplinary approach and a high index of suspicion. C4d deposition does not appear to be a necessary criterion for the diagnosis, and although some cases may initially respond to therapy, there is a high incidence of CLAD and poor survival after AMR. This article is protected by copyright. All rights reserved.

Immunological requirements for rejection and tolerance induction differ between various organs. While memory CD8+ T cells are considered a barrier to immunosuppression-mediated acceptance of most tissues and organs, tolerance induction after lung transplantation is critically dependent on central memory CD8+ T lymphocytes. Here we demonstrate that costimulation blockade-mediated tolerance after lung transplantation is dependent on programmed cell death 1 (PD-1) expression on CD8+ T cells. In the absence of PD-1 expression, CD8+ T cells form prolonged interactions with graft-infiltrating CD11c+ cells; their differentiation is skewed towards an effector memory phenotype and grafts are rejected acutely. These findings extend the notion that requirements for tolerance induction after lung transplantation differ from other organs. Thus, immunosuppressive strategies for lung transplant recipients need to be tailored based on the unique immunological properties of this organ.

Long-term survival after lung transplantation remains profoundly limited by graft rejection. Recent work has shown that bronchus-associated lymphoid tissue (BALT), characterized by the development of peripheral nodal addressin (PNAd)-expressing high endothelial venules and enriched in B and Foxp3+ T cells, is important for the maintenance of allograft tolerance. Mechanisms underlying BALT induction in tolerant pulmonary allografts, however, remain poorly understood. Here, we show that the development of PNAd-expressing high endothelial venules within intragraft lymphoid follicles and the recruitment of B cells, but not Foxp3+ cells depends on IL-22. We identify graft-infiltrating gamma-delta (γδ) T cells and Type 3 innate lymphoid cells (ILC3s) as important producers of IL-22. Reconstitution of IL-22 at late time points through retransplantation into wildtype hosts mediates B cell recruitment into lymphoid follicles within the allograft, resulting in a significant increase in their size, but does not induce PNAd expression. Our work has identified cellular and molecular requirements for the induction of BALT in pulmonary allografts during tolerance induction and may provide a platform for the development of new therapies for lung transplant patients.

Liver NRH is seen in all patients age; however, more frequently in those over the age of 60 years and associated with multiple systemic diseases. In liver allograft recipients, the development of DnNRH has been linked with the use of azathioprine or vascular abnormalities. We present the clinicopathologic characteristics of 17 pediatric patients who underwent liver transplantation and subsequently developed DnNRH. The patients were divided into early and late onset depending if DnNRH was diagnosed within or beyond 4 years after transplant. Eight patients (47%) presented as early onset, of which two had normal ultrasound at time of diagnosis. One patient (12.5%) with early onset lost the graft secondary to DnNRH. Nine patients (53%) presented as late onset, of which two (22%) had normal ultrasound at time of diagnosis. Two patients (25%) of the late onset lost their graft secondary to chronic rejection and DnNRH. Two patients (12%) died secondary to cytomegalovirus pneumonitis and pancolitis. Furthermore, both groups presented with symptoms differing from the adult population in prior studies and were not associated with the use of azathioprine or vascular abnormalities. Interestingly, episodes of acute cellular rejection were more common in the early-onset group compared to the late-onset group. In conclusion, DnNRH in the pediatric age group has a different clinical presentation, possibly reflecting a different pathogenesis compared to the adult population.

Identify and characterize pediatric pulmonary emboli present at autopsy.Retrospective single institution observational study with clinicopathologic correlation.Tertiary medical center.All autopsy cases performed at Washington University from 1997 to 2017 in pediatric patients (≤ 18 yr old).Of 1,763 pediatric autopsies, 13 cases of pulmonary emboli were identified, including thromboemboli (6/13, 46.1%), septic emboli (3/13, 23.1%), fat emboli, and foreign body emboli.Pulmonary embolus is a relatively rare but potentially fatal cause of death in pediatric age patients and is often associated with congenital abnormalities, malignancy, or recent surgical procedures. Half of the fatal pulmonary emboli found in our series (3/6) show microscopic and diffuse, rather than large central or saddle emboli, potentially make a clinicoradiographic diagnosis more difficult. This series is also the first to report a case of hemostatic matrix pulmonary embolism in a pediatric age patient.

Nearly all patients with small cell lung cancer (SCLC) eventually relapse with chemoresistant disease. The molecular mechanisms driving chemoresistance in SCLC remain un-characterized. Here, we describe whole-exome sequencing of paired SCLC tumor samples procured at diagnosis and relapse from 12 patients, and unpaired relapse samples from 18 additional patients. Multiple somatic copy number alterations, including gains in ABCC1 and deletions in MYCL, MSH2, and MSH6, are identifiable in relapsed samples. Relapse samples also exhibit recurrent mutations and loss of heterozygosity in regulators of WNT signaling, including CHD8 and APC. Analysis of RNA-sequencing data shows enrichment for an ASCL1-low expression subtype and WNT activation in relapse samples. Activation of WNT signaling in chemosensitive human SCLC cell lines through APC knockdown induces chemoresistance. Additionally, in vitro-derived chemoresistant cell lines demonstrate increased WNT activity. Overall, our results suggest WNT signaling activation as a mechanism of chemoresistance in relapsed SCLC.

This chapter considers the clinicopathologic features of pseudoneoplastic pulmonary and pleural lesions. They include pulmonary hamartomas, inflammatory pseudotumor, plasma cell granuloma, Rosai-Dorfman disease, extramedullary hematopoiesis, tumefactive manifestations of lung injury, peribronchiolar metaplasia, mesothelial hyperplasia, hyaline pleural plaques, and diffuse pleural fibrosis. The specialized morphologic features of those lesions are discussed, with emphasis on differential diagnosis with other pathologic entities.

This chapter considers the clinicopathologic features of borderline and malignant mesothelial pleural neoplasms. They include “well-differentiated papillary mesothelioma,” multicystic mesothelial tumors of borderline biological potential, and malignant mesotheliomas. The specialized morphological features of those lesions are discussed, with emphasis on differential diagnosis with other tumors.

Memory T lymphocytes are commonly viewed as a major barrier for long-term survival of organ allografts and are thought to accelerate rejection responses due to their rapid infiltration into allografts, low threshold for activation, and ability to produce inflammatory mediators. Because memory T cells are usually associated with rejection, preclinical protocols have been developed to target this population in transplant recipients. Here, using a murine model, we found that costimulatory blockade-mediated lung allograft acceptance depended on the rapid infiltration of the graft by central memory CD8+ T cells (CD44(hi)CD62L(hi)CCR7+). Chemokine receptor signaling and alloantigen recognition were required for trafficking of these memory T cells to lung allografts. Intravital 2-photon imaging revealed that CCR7 expression on CD8+ T cells was critical for formation of stable synapses with antigen-presenting cells, resulting in IFN-γ production, which induced NO and downregulated alloimmune responses. Thus, we describe a critical role for CD8+ central memory T cells in lung allograft acceptance and highlight the need for tailored approaches for tolerance induction in the lung.

Dr. Louis Dehner is an internationally renowned surgical pathologist who has published multiple textbooks and has authored or co-authored nearly 400 original articles in the medical literature. While many think of him as a pediatric pathologist, he has contributed to the literature across virtually the entire breadth of surgical pathology, and the lung and pleura is no exception. This review will highlight Dr. Dehner׳s contributions to the pulmonary and pleural pathology literature in the areas of infectious disease, medical lung disease and transplant pathology, and a number of neoplasms of the lung and pleura, with the remainder of this manuscript dedicated to the still evolving story of the pleuropulmonary blastoma as the signature contribution of his long and distinguished career.

Clostridial myonecrosis is an uncommon, highly lethal necrotizing soft tissue infection. The source may be occult at the time of clinical presentation. In cases caused by Clostridium septicum, there is an association with colorectal malignant disease, suggesting that underlying colonic pathology frequently is the source of the infection.Case report and literature review.A 37-year old man with acquired immunodeficiency syndrome, end-stage renal disease, and C. difficile colitis presented to the Emergency Department (ED) with a primary complaint of abdominal pain and incidental right forearm pain. While undergoing evaluation in the ED, he developed progressive erythema, edema, and emergence of bullae over his right forearm. After rapid imaging of his abdomen, he underwent guillotine amputation of his right upper extremity because of extensive myonecrosis and total abdominal colectomy secondary to right colonic necrosis and C. difficile colitis. Blood cultures were positive for C. septicum. Microscopic examination of both the necrotic colon and the right forearm musculature demonstrated invasion of gram-positive bacilli throughout.Myonecrosis caused by C. septicum frequently occurs in the presence of colonic pathology, typically malignant disease. This case report illustrates the development of this pathological process in an immunosuppressed patient who did not have colon cancer, but rather colonic mucosal inflammation produced by C. difficile.

Objective: To evaluate the use of inflation-fixed lung tissue for emphysema quantification with CT and 3He MR diffusion imaging. Methods: Fourteen subjects representing a range of chronic obstructive pulmonary disease severity who underwent complete or lobar lung resection were studied. CT measurements of lung attenuation and MR measurements of the hyperpolarized 3He apparent diffusion coefficient (ADC) in resected specimens fixed in inflation with heated formalin vapor were compared with measurements obtained before fixation. Results: The mean CT emphysema index was 56% ± 17% before and 58% ± 19% after fixation (P=0.77;R=0.76). Index differences correlated with differences in lung volume (R2=0.47). The mean 3He ADC was 0.40 ± 0.15 cm2/sec before and 0.39 ± 0.14 cm2/sec after fixation (P=0.03, R=0.98). The CT emphysema index and the 3He ADC were correlated before (R=0.89) and after fixation (R=0.79). Conclusion: Concordance of CT and 3He MR imaging measurements in unfixed and inflation-fixed lungs supports the use of inflation-fixed lungs for quantitative imaging studies in emphysema.

Rationale and Objectives Computed tomography (CT) section thickness and reconstruction kernel each influence CT measurements of emphysema. This study was performed to assess whether their effects are related to the magnitude of the measurement. Materials and Methods Low-radiation-dose multidetector CT was performed in 21 subjects representing a wide range of emphysema severity. Images were reconstructed using 20 different combinations of section thickness and reconstruction kernel. Emphysema index values were determined as the percentage of lung pixels having attenuation lower than multiple thresholds ranging from −960 HU to −890 HU. The index values obtained from the different thickness-kernel combinations were compared by repeated measures analysis of variance and Bland-Altman plots of mean versus difference in all subjects, and correlated with quantitative histology (mean linear intercept, Lm) in a subset of resected lung specimens. Results The effects of section thickness and reconstruction kernel on the emphysema index were significant ( P r = 0.55–0.68 ( P = .007–.03). Conclusion The effects of CT section thickness and kernel on emphysema index values varied systematically with the magnitude of the emphysema index. All reconstruction techniques provided significant correlations with quantitative histology.

Asbestosis has long been defined as a diffuse interstitial "fibrotic" process, in similarity to other chronic interstitial pulmonary diseases. To address the hypothesis (which was based on morphological nuances) that the interstitial connective tissue response in asbestosis may be fibroelastotic rather than fibrotic, a comparative characterization of the connective response in cases of asbestosis and other forms of interstitial lung disease was performed. Archival open lung biopsies or autopsy specimens of pulmonary diseases featuring interstitial connective tissue abnormalities (15 of asbestosis, 21 of organizing pneumonia, 15 usual interstitial pneumonitis/idiopathic pulmonary fibrosis [IPF], 9 organizing diffuse alveolar damage, 9 "nonspecific" interstitial pneumonitis, 4 sarcoidosis, 3 each of desquamative interstitial pneumonia and chronic amiodarone toxicity, 2 cryptogenic organizing pneumonias, and 1 each of chronic hypersensitivity pneumonitis and chronic eosinophilic pneumonitis [85 total]) were stained histochemically with hematoxylin and eosin, Perl's method, Gomori's trichrome procedure, and the Verhoeff-van Gieson technique. Representative subsets of the cases (n = 20) were also studied immunohistologically using an antibody to elastin. Fibroelastosis in each of the samples was assessed for the degree of response and its location using a 3-tiered scale. The degree of fibroelastosis in the 15 cases of asbestosis was variable, with the pattern being peribronchial and perivascular in all instances; at least 2 asbestos bodies were identified in fibroelastotic foci in each of the 15 cases as highlighted with Perl's stain. Forty-seven cases of nonasbestotic lung disease (71%) showed interstitial fibrosis with a variable (usually modest) amount of admixed elastic tissue; when present, elastic fibers were distributed in a diffuse interstitial pattern, with or without perivascular accentuation. All cases of IPF also showed areas of fibroelastosis, but those foci were confined to regions of overt "honeycomb" change. No asbestos bodies were seen in any disease except asbestosis, and a predominantly peribronchial pattern of fibroelastosis was not identified in any nonasbestotic interstitial lung disease in this study. The authors conclude that the types and patterns of pulmonary connective tissue response in interstitial lung diseases may provide additional diagnostic clues to the presence of asbestosis.

To characterize the effect of diffusion time on short-range hyperpolarized (3)He magnetic resonance imaging (MRI) diffusion measurements across a wide range of emphysema severity.(3)He diffusion MRI was performed on 19 lungs or lobes resected from 18 subjects with varying degrees of emphysema using three diffusion times (1.6 msec, 5 msec, and 10 msec) at constant b value. Emphysema severity was quantified as the mean apparent diffusion coefficient (ADC) and as the percentage of pixels with ADC higher than multiple thresholds from 0.30-0.55 cm(2)/sec (ADC index). Quantitative histology (mean linear intercept) was obtained in 10 of the lung specimens from 10 of the subjects.The mean ADCs with diffusion times of 1.6, 5.0, and 10.0 msec were 0.46, 0.40, and 0.37 cm(2)/sec, respectively (P0.0001, analysis of variance [ANOVA]). There was no relationship between the ADC magnitude and the effect of diffusion time on ADC values. The mean linear intercept correlated with ADC (r = 0.91-0.94, P0.001) and ADC index (r = 0.78-0.92, P0.01) at all diffusion times.Decreases in ADC with longer diffusion time were unrelated to emphysema severity. The strong correlations between the ADC at all diffusion times tested and quantitative histology demonstrate that ADC is a robust measure of emphysema.

Objective: To determine the safety and efficacy of saline-linked surface radiofrequency ablation (SLSRFA) in a clinical setting. Summary Background Data: We have previously identified safe and effective parameters for use of SLSRFA in a porcine model. Methods: An initial study was conducted to determine if parameters defined in the porcine model were safe and effective in human livers. In 16 patients undergoing liver resection, normal areas of liver were treated with SLSRFA using various power/diameter combinations (10 W/1 cm; 15 W/2 cm; 45 W/4 cm) for 9 minutes with and without inflow occlusion. In a second study, superficial hepatic colorectal cancer (CRC) metastases were treated at 45 W/4 cm for 9 minutes without inflow occlusion in 11 patients. Ablation depth was measured and samples were examined for cell viability by nicotine adenine dinucleotide stain. This study was registered in the ClinicalTrials.gov database and has the following ID number, NCT00869843. Results: Ablation depth in normal liver varied from 3 to 20 mm. Depth was significantly dependent on power, lesion size, and inflow occlusion. Nicotine adenine dinucleotide stains showed total cell necrosis to the full depth of ablation. In the second study, large hepatic CRC metastases showed total cell necrosis to a mean depth of 12 mm. Two tumors less than 7 mm in depth showed complete necrosis. Metastases were more susceptible to SLSRFA than normal liver. Conclusion: SLSRFA completely and safely ablates normal liver to a depth of at least 4 mm at 45 W/4 cm treatment parameters. Remarkably, it is even more effective in ablating metastatic CRC. SLSRFA is an effective tool for extending resection margins and for ablating superficial small tumors or superficial parts of large tumors.

Expression of gastrointestinal biomarkers MUC1, MUC2, MUC5AC, small-intestinal mucin antigen (SIMA), villin, and CDX2 has been studied in colorectal adenocarcinoma (CRC). Little is known, however, about their expression in small-intestinal adenocarcinoma (SIA). We immunohistochemically compared 30 SIAs with 48 CRCs for the expression of these biomarkers. The results showed that all 6 proteins were variably expressed in SIA, but the frequencies of expression were significantly lower than those for CRC with the exception of MUC1. Specifically, positive staining for MUC1, MUC2, MUC5AC, SIMA, villin, and CDX2 was observed in 16 (53%), 17 (57%), 12 (40%), 15 (50%), 20 (67%), and 18 (60%) of SIAs and 25 (52%), 43 (90%), 39 (81%), 45 (94%), 47 (98%), and 47 (98%) of CRCs, respectively. In addition, SIAs more frequently exhibited a focal staining pattern for MUC2, MUC5AC, SIMA, and villin, whereas more diffuse immunoreactivity was evident in CRCs. Focal staining for MUC1 and diffuse staining for CDX2 were common for SIAs and CRCs. Furthermore, poorly differentiated SIAs tended to express MUC1 more frequently when compared with well- and moderately differentiated SIAs. These observations further support the notion that SIA is immunophenotypically distinct from CRC despite their morphologic similarity.

In the skin, separation of selected lymphomas from lymphoid hyperplasia can be challenging. The authors examined 45 cutaneous lymphomas, excluding mycosis fungoides (26 small lymphocytic or mixed tumors; 19 large cell lymphomas), 10 "atypical" lesions, and 40 lesions of presumed lymphoid hyperplasia, comparing morphologic attributes of such proliferations with their immunophenotypes in paraffin sections. The object of this study was to determine whether immunologic data obtained from routinely-processed specimens could be used to further objectify morphologic interpretations. Features favoring lymphoma included a lesional epicenter in the lower dermis or subcutis; poor circumscription of lymphoid aggregates; and dissection of lymphoid cells between collagen bundles. Immunostains included antibodies to CD20, CD43, CD45, CD45RO, CD45RA, CD68, proliferating cell nuclear antigen (PCNA), and MB2. Eleven of 26 small lymphocytic or mixed-cell lymphomas and 3 of 10 "atypical" cases demonstrated an abnormal immunophenotype, including co-expression of CD43 and CD20 or non-physiological CD45RA distribution. In contrast, none of 40 cases with benign features manifested aberrant antigen expression. Thirty-one of 37 cases in which > or = 75% of the cells typed as B lymphocytes showed malignant morphologic features, 5 were "atypical" and possibly lymphomatous, and only one had benign features. PCNA stains showed greater positivity of the lymphoid nuclei in lymphomas, and a labeling index of > 30% was correlated with malignancy in this context. These observations indicate that immunostaining may provide useful adjunctive information in distinguishing benign from malignant cutaneous lymphoid proliferations in paraffin sections.

Sarcomatoid carcinomas are rare malignancies which represent poorly differentiated epithelial tumors that may be difficult to recognize as such. While some cases may have obvious epithelial areas, the sarcomatoid areas are poorly distinguishable from true sarcoma at the light microscopic level and, by immunohistochemistry, often show only limited staining for traditional epithelial markers such as cytokeratin or epithelial membrane antigen. This can be particularly problematic for diagnosis on small biopsy specimens. We sought to assess the diagnostic utility of several immunohistochemical markers of epithelial differentiation including p63, MOC-31, and thyroid transcription factor-1 on sarcomatoid carcinomas of the head and neck (19 cases; 'spindle cell carcinomas'), lung (19 cases), and urinary bladder (11 cases). These results were compared to immunohistochemistry for the traditional epithelial markers pan-cytokeratin and epithelial membrane antigen. Staining for p63 showed the greatest diagnostic utility, positive in 63, 50, and 36% of head and neck, lung, and urinary bladder sarcomatoid carcinomas, respectively. p63 stains were positive in many cases where immunohistochemistry was negative for both pan-cytokeratin and epithelial membrane antigen. All three alternative markers were quite specific for epithelial differentiation, each staining less than 10% of the control group of 73 various primary and metastatic sarcomas, melanomas, and benign spindle cell lesions. In conclusion, immunostaining beyond traditional pan-cytokeratin and epithelial membrane antigen may have diagnostic utility in this context.

Background The Lung Rejection Study Group (LRSG) created a scheme for grading acute allograft rejection in 1990 and then revised it in 1996, but virtually no studies have evaluated the reliability of this formulation. This investigation assessed the reliability of the current LRSG system by determining inter- and intrareader agreement for grading transbronchial biopsy samples from lung transplant recipients. Methods Biopsy samples from a cohort of 204 recipients were reviewed and classified by a single pathologist who was blinded to original interpretations. The "A" and "B" rejection grades from this contemporary review were compared with original grades by the kappa statistic. Results For "A" grading, weighted kappa was 0.65 (95% confidence interval [CI] 0.60–0.70) for interreader agreement ( n = 529 specimens) and 0.65 (95% CI 0.53–0.76) for intrareader agreement ( n = 97 specimens). For "B" grading, weighted kappa was 0.26 (95% CI 0.14–0.39) for interreader agreement ( n = 164 specimens) and 0.33 (95% CI 0.15–0.51) for intrareader agreement ( n = 58 specimens). Conclusions On the basis of the analysis of the LRSG scheme, "A" grades exhibit very good reliability, but "B" grades have only fair reliability, and steps to improve this shortcoming should be taken.

Objective Multiple gene transfer might permit modulation of concurrent biochemical pathways involved in acute lung graft rejection. We investigated whether gene cotransfection into the recipient reduces acute lung graft rejection. Methods Brown Norway rats were used as donors, and F344 rats were used as recipients. Recipient animals were injected with saline (groups I/VI) or 1 × 10 10 pfu of adenovirus encoding β-galactosidase (groups II/VII), transforming growth factor β1 (groups III/VIII), interleukin 10 (groups IV/IX), or both transforming growth factor β1 and interleukin 10 (groups V/X) into both leg muscles 2 days before transplantation (groups I-V) or at the time of harvest (groups VI-X). The Kruskal-Wallis test for rejection score and 1-way analysis of variance were used to compare groups. Results Oxygenation was significantly improved in the cotransfected groups treated 2 days before transplantation and at the time of harvest. Rejection scores were also reduced in the cotransfected groups. In group V cotransfection suppressed endogenous interleukin 2 but not interferon γ and tumor necrosis factor α. Conclusion Recipient intramuscular cotransfection of transforming growth factor β1 and interleukin 10 suppressed interleukin 2 expression and provided a synergistic effect that reduced acute lung graft rejection. This approach might be applied to the clinical setting because transplant recipients could be treated at the time of implantation.

We studied 68 sporadic colorectal carcinomas (CRCs) with medullary features (MCRCs) and compared them with 35 poorly differentiated purely "enteric" CRCs (ECRCs) and 15 purely neuroendocrine carcinomas (NECs) of grades II and III, all in patients lacking a family history of CRC. Potential clinicopathologic differences between the study groups were assessed. MCRCs were significantly more common in the ascending colon than were ECRCs, but there was no significant dissimilarity to NECs. ECRCs occurred more often in the rectosigmoid than MCRCs or NECs. MCRCs arose in older patients, and a marked sex difference also was noted. Despite an infiltrative growth pattern, MCRC was less likely than ECRC to manifest with stage III or IV disease, but there was no stage-related difference from NECs. Although the histologic images of MCRCs were evocative of neuroendocrine differentiation, chromogranin positivity and synaptophysin reactivity in that group did not differ meaningfully from that of ECRCs but was dissimilar to the 100% labeling of NECs. p53 immunolabeling was similar in the 3 tumor groups. Follow-up data in the study cases showed that 5-year mortality was 40% (27/68) for MCRC, 59% (19/32) for ECRC, and 93% (14/15) for NEC. Medullary CRC seems to be a distinct clinicopathologic variant of CRC, which does not have a neuroendocrine lineage. The biologic behavior of MCRC was better than that of ECRC or NEC.

Fulguration of surface tumors using radiofrequency (RF) energy is a well-established technique. However, the depth of tissue destruction has been limited to a few millimeters because of charring of the surface at the point of electrode contact. Charring converts the surface from a good to a poor electrical conductor, and causes such a steep rise in the impedance (resistance) that current effectively ceases. This limits the depth of tissue destruction. Therefore fulguration has not been useful for solid organ tumors such as hepatic tumors. Saline-linked surface radiofrequency ablation is a new technique designed to prevent surface charring. The strategy was first applied to catheter ablation of cardiac lesions.1 The saline-linked RF device provides a continuous flow of saline, a good coolant, and electrical conductor that maintains the temperature of the surface below 100°C. Charring does not occur, and greater depths of tissue destruction are possible. However, although the surface is maintained below 100°C, temperatures in the subsurface may rise above 100°C. This can lead to steam formation and expansion and then to disruption of the surface. This undesirable side effect is called “steam popping.”2,3 This study had 2 purposes. The first was to determine factors that lead to steam popping and, subsequently, to learn how to avoid it. Once safe nonpopping parameters were established, it was possible to pursue the second aim, which was to determine factors that affect the depth of tissue destruction. Of particular interest was the effect of inflow occlusion, which has been shown to extend the size of ablations induced by interstitial radiofrequency electrodes.4

Objective: Gene transfer to experimental lung grafts has been shown to reduce ischemia-reperfusion injury and acute rejection. The optimal delivery route should produce high lung expression with no inflammation and minimal systemic expression. The goal of this study was to determine the optimal gene transfer route for use in experimental lung transplantation. Methods: F344 rats were injected with 2.9 × 1010 plaque-forming units of adenovirus vector encoding β-galactosidase through intratracheal, intravenous, intraperitoneal, or intramuscular delivery routes and killed 48 hours later. Gene expression was measured by means of enzyme-linked immunosorbent assay. Results: Intratracheal delivery produces significantly greater gene expression in the lung (75,350 ± 47,288 pg/100 μg of protein, P

Objective: Multiple gene transfer might permit modulation of concurrent biochemical pathways involved in lung graft ischemia-reperfusion injury. In this study we analyzed whether recipient intramuscular naked plasmid cotransfection of transforming growth factor β1 and interleukin 10 would result in amelioration of lung graft ischemia-reperfusion injury. Methods: Forty-eight hours before transplantation, 6 groups (n = 6) of F344 rats received intramuscular injection of naked plasmid encoding chloramphenicol acetyltransferase, chloramphenicol acetyltransferase plus β-galactosidase, transforming growth factor β1, interleukin 10, or transforming growth factor β1 plus interleukin 10 or were not treated. Donor lungs were flushed and stored for 18 hours at 4°C before transplantation. Twenty-four hours later, grafts were assessed immediately before the animals were killed. Arterial oxygenation, wet/dry ratio, myeloperoxidase, and proinflammatory cytokines (interleukin 1, tumor necrosis factor α, interferon γ, and interleukin 2) were measured, and immunohistochemistry was performed. Results: For lung graft function, the arterial oxygenation was considerably higher in the cotransfected group receiving transforming growth factor β1 plus interleukin 10 compared with that in all other groups (P ≤.03). The wet/dry ratio, reflecting lung edema, was reduced in the cotransfected group compared with that in control animals (nontreated, P

Background . Gene transfer into the donor graft has been demonstrated to be feasible in reducing ischemia-reperfusion injury and rejection in lung transplantation. This study was undertaken to determine whether intramuscular gene transfer into the recipient can also reduce subsequent lung graft rejection. Methods . Brown Norway rats served as donors and F344 rats as recipients. Recipient animals were injected with 10 10 plaque-forming units of adenovirus encoding active transforming growth factor β1 (group I, n=6), β-galactosidase as adenoviral controls (group II, n=6), or normal saline without adenovirus (group III, n=6) into both gluteus muscles 2 days before transplantation. Gene expression was confirmed by enzyme-linked immunosorbent assay. Graft function was assessed on postoperative day 5. Results . Successful gene transfection and expression were confirmed by the presence of active transforming growth factor β1 protein in muscle and plasma. Oxygenation was significantly improved in group I (group I vs II and III, 353.6 ± 63.0 mm Hg vs 165.7 ± 39.9 and 119.1 ± 41.5 mm Hg; p = 0.02 and 0.004). The muscle transfected with the transforming growth factor β1 showed granulation tissue with fibroblast accumulation. Conclusions . Intramuscular adenovirus-mediated gene transfer of active transforming growth factor β1 into the recipients attenuates acute lung rejection as manifested by significantly improved oxygenation in transplanted lung allografts. This intramuscular transfection approach as a cytokine therapy is feasible in transplantation and may be useful in reducing rejection as well as reperfusion injury.

Recent studies suggest that viral interleukin-10 (vIL-10) suppresses alloimmune response in transplantation. Tissue mRNA expression of inducible nitric oxide synthase (iNOS) and exhaled nitric oxide (NO) levels have been observed to increase in lung allograft rejection. The aims of this study were to examine the feasibility of vIL-10 gene transfer into rat lung allografts and to investigate its effect on subsequent allograft rejection.Male Lewis rats (RT1l) underwent left lung transplantation with allografts from Brown Norway rats (RT1n). The donor rats were endobronchially transfected 2 minutes before harvest with 400 microg (group I, n = 5), 600 microg (group II, n = 5), or 800 microg (group III, n = 5) of naked pCMVievIL-10. Group IV (n = 5) animals, serving as control, received 400 microg of naked pCF1-CAT. All recipients were sacrificed on postoperative day 5. Transgene expression of vIL-10 was assessed by both reverse transcriptase-polymerase chain reaction and immunohistochemistry. Allograft gas exchange, exhaled NO level, histologic rejection score, and mRNA expression of graft cyokines were also assessed.Transgene expression of lung graft vIL-10 was detected by both reverse transcriptase-polymerase chain reaction and immunohistochemistry. The iNOS mRNA expression in groups I, II, and III was significantly lower than that of group IV (p0.05, analysis of variance). Exhaled NO levels in groups I, II, and III were significantly lower than in group IV (p0.01, analysis of variance). There was no significant difference between groups with respect to gas exchange, peak airway pressure, or histologic rejection score.It appears that endobronchial transfection of naked vIL-10 plasmid in a rat lung allotransplant model is feasible and suppresses lung iNOS mRNA expression and exhaled NO levels. An association between iNOS upregulation and high exhaled NO levels in lung allograft resection was also noted.

We describe 2 men, ages 69 and 49 years, who experienced fatal rupture of pulmonary infarcts. Both patients had documented prior thromboembolic events and subsequently had abrupt deterioration in cardiorespiratory function. Autopsies showed massive unilateral hemothorax in both patients. Rupture of a pulmonary infarct may occur spontaneously or iatrogenically due to aggressive anticoagulation. This may be difficult to distinguish from secondary hemothorax with an intact pleura, but rupture typically has a considerably more rapid clinical evolution. Treatment should include immediate withdrawal of thrombolytic or anticoagulant medications and evacuation of the pleural space. Surgical intervention can be considered, although the utility of that approach must await prospective trials.

Diagnostic immunohistology (DIHC) is a discipline that has been used clinically for at least two decades, but, because of medicolegal encumbrances, it has not been a part of many formal outcomes analyses during that time. Potential applications of this technology with a direct bearing on response to treatment include the accurate identification of infectious organisms, distinction between morphologically-similar undifferentiated tumors, separation of benign and malignant neoplasms, and prognostication of malignancies. The first two of those four roles may indeed have a quantifiable impact on case outcomes, but the last two applications have only questionable value in this specific context. This is an area of medicine in which formal outcomes analysis is greatly needed to help determine future practice patterns.

We investigated endobronchial transfection of CAT and TGF-beta1 cDNA selectively delivered to the lung graft with or without liposomes.Phase I: F344 rats received 130 microg of naked plasmid pCF1-CAT or complexed to liposome GL67 via left main bronchus instillation. Rats were awakened (pCF1-CAT, n = 4; GL67:pCF1-CAT, n = 4) or served as donors in an isogenic transplant (pCF1-CAT, n = 5; GL67:pCF1-CAT, n = 5). ELISA was performed on lungs, hearts, and livers on POD 2. Phase II: BN lungs received TGF-beta1 sense (n = 6); antisense (n = 5); GL67:TGF-beta1 sense (n = 10); or saline solution (n = 10). F344 recipients were sacrificed on POD 5. The arterial pO2 and rejection were assessed. RT-PCR for murine TGF-beta1 was performed.Phase I: CAT expression was 519+/-287 pg and 63+/-68 with pCF1-CAT and 104+/-67 and 37+/-45 with GL67:pCF1-CAT, respectively, in the non-transplant and in the transplant setting. No protein was detected in the hearts, livers, and in the native lung of the recipients. Phase II: RT-PCR confirmed murine TGF-beta1 transfection. pO2 was 362.7+/-110.2 (mean mm Hg +/- SD) for sense TGF-beta1; 146.88+/-85.5 for antisense; 241.5+/-181.5 for GL67-TGF-beta1 sense; and 88.4+/-38.7 for saline. TGF-beta1 sense versus all other groups, p0.05, GL67-TGF-beta1 sense versus saline, p = 0.01. Rejection was significantly lower for TGF-beta1 sense versus saline, p = 0.04.Endobronchial administration of naked plasmid achieves selective transfection of lung grafts. Using this strategy, TGF-beta1 reduces early lung allograft rejection.

Transforming growth factor alpha (TGF-alpha) is expressed in respiratory epithelial cells and alveolar macrophages during development and following lung injury. In the present study, the presence and sites of synthesis of TGF-alpha and its receptor, the epidermal growth factor receptor (EGF-R), were assessed in lung tissue from patients with severe lung disease caused by cystic fibrosis (CF). Lung sections from 24 individuals with CF, obtained at the time of lung transplantation, were compared to lung sections from five lung donors without CF. Cellular sites of TGF-alpha, EGF-R, and cellular sites of proliferation were assessed by immunohistochemistry. All CF lung sections contained multiple cell types with detectable TGF-alpha. Compared to control sections, intensity of TGF-alpha immunostaining in macrophages, airway epithelial cells, and peribronchial submucosal cells was increased. EGF-R was detected in respiratory epithelial and peribronchial stromal cells but not in alveolar macrophages. The intensity of EGF-R staining in CF lung tissue did not differ from that of controls. An increased number of cells expressing Ki-67 nuclear antigen was detected in peribronchial submucosal cells but not bronchiolar epithelial cells in the CF lungs. The increased expression of TGF-alpha in CF lung tissue supports the concept that TGF-alpha plays a role in paracrine/autocrine regulation of lung remodeling associated with injury and repair in the lungs of individuals with cystic fibrosis.

Spindle cell proliferations of the skin are diverse, both morphologically and mechanistically. The authors have encountered four examples of a distinctive reactive/reparative cutaneous spindle cell lesion that shows homology with ones seen in the genitourinary tract and oral cavity and that is known as "postoperative/posttraumatic spindle cell nodule" (PSCN). These occurred in the skin of the face and scalp (2 cases), arm (1 case), and vulvar skin (one case), and were clearly related historically to prior episodes of trauma. The proliferations were characterized by variably-apposed and cytologically-bland spindle cells with numerous mitotic figures, set in a highly vascular stroma containing extravasated erythrocytes and inflammatory cells. All lesions were immunoreactive for vimentin, actin, and desmin, with no labeling for keratin. Postoperative/posttraumatic spindle cell nodule of the skin is a significant pseudoneoplastic lesion that is related (and perhaps identical pathogenetically) to nodular fasciitis; as such, it may be mistaken for a sarcoma or a spindle cell carcinoma. Careful attention to clinicopathologic and histologic details should result in its accurate recognition.

The diagnosis of gastrointestinal (GI) lymphoid infiltrates can be challenging when based only on conventional microscopic assessment. When marked cytologic atypia is present, a diagnosis of malignant neoplasm is readily made; however, the distinction between a low-grade malignant neoplasm and a reactive process is much more difficult. If unfixed tissue is available, immunohistologic or genotypic methods that are usually aimed at defining B-lymphocytic monotypism can be applied. However, paraffin-embedded tissue has generally been deemed unsuitable for these techniques. We assessed the value of a panel of immunohistochemical stains and a seminested polymerase chain reaction (PCR) for the analysis of lymphoid infiltrates in routinely processed GI biopsy specimens from 49 archival cases, including morphologically benign, indeterminate, and overtly malignant lesions. Clinical outcome was used as the retrospective diagnostic standard; end points were death (of lymphomatous disease or otherwise) and clinical evidence of lymphoma. According to light microscopic criteria, 19 cases were classified as benign, 17 as malignant, and 13 as atypical. Immunophenotyping correctly identified 28 of 31 benign and 14 of 18 malignant lesions (7 cases had an indeterminate immunoprofile). Genotypic analysis correctly identified 12 of 18 malignant and 29 of 31 benign lesions, but spurious monoclonal bands were produced by PCR amplification of 2 of the latter 31 cases. No single technique exists for correct categorization of all paraffin-embedded specimens of GI lymphoid infiltrates. We recommend a sequential approach to the use of available diagnostic modalities.

Study objective To determine the diagnostic yield of histologic specimens obtained by postmortem transbronchial biopsy (TBB) in patients with acute respiratory failure requiring mechanical ventilation. Design Standard postmortem histologic examination of lung tissue specimens. Setting An urban university-affiliated hospital. Patients or participants Thirty patients with diffuse pulmonary infiltrates and acute respiratory failure, who underwent postmortem examination. Interventions Following removal of the lungs from the thorax. TBBs were obtained from the lower lobe of each deflated lung and comparison was made to a 1-cm 3 tissue block obtained from the ipsilateral lower lobe. Measurements and results Standard postmortem histologic examination provided a specific diagnosis in 85% of the 60 lungs examined, and histologic evidence of acute pneumonia was present in 30% of the lungs. The overall yield of TBB was 48% for establishing a specific histologic diagnosis and 15% for the diagnosis of acute pneumonia. Using standard postmortem histologic examination as the gold standard, the sensitivity and specificity of TBB for making a specific diagnosis were 57% and 100% respectively, with corresponding positive and negative predictive values of 100% and 29%. For the histologic diagnosis of acute pneumonia, the sensitivity of TBB was 50%, the specificity was 100%, and the positive and negative predictive values were 100% and 82%, respectively. The kappa statistic for the agreement between the two diagnostic methods was 0.28 for establishing a specific diagnosis and 0.58 for the diagnosis of acute pneumonia. Obtaining 12 TBBs rather than six TBBs did not increase the diagnostic yield for TBB. Conclusions These findings suggest poor overall agreement between standard postmortem histologic examination and TBB specimens. Although not performed in a clinical setting, this postmortem investigation suggests that TBB may be of limited value in mechanically ventilated patients with acute respiratory failure because of its low sensitivity.

Mutations in the p53 tumor suppressor gene, located at chromosomal locus 17pI3, are the most commonly seen genetic alterations found in human malignancies. Their role in the pathogenesis of malignant melanoma is thought to be limited, although variable results have been reported in reference to immunoreactivity for putatively mutant p53 protein (mp53) in melanocytic lesions in general. In that light, the authors undertook an immunohistologic evaluation of 256 well-characterized tumors in that category, including common nevi (CN; n=73); Spitz nevi (SN; n=40); nodular melanomas (NMMs; n=32), superficial spreading melanomas (SMMs; n=65); lentigo maligna melanomas (LMMs; n=23); and melanomas arising in preexisting nevi (MANs; n=23). One hundred cells were counted manually in randomly selected high-power microscopic fields, in regard to nuclear labeling for mp53. Results were recorded semiquantitatively, as negative, positive (1-4% of tumor cells); and positive (>5% of tumor cells). No examples of CN or SN demonstrated any immunoreactivity whatever for mp53, whereas 105 of 143 melanomas (73%) did so. However, an mp53 index of >50% was seen in only 29% of the latter lesions. NMMs were most often mp53-positive and showed the highest numerical level of nuclear labeling, followed in respective order by SMMs, and LMMs/MANs. These results suggest that negative mp53-immunostaining cannot be equated with the diagnostic interpretation of a benign melanocytic neoplasm, because 27% of melanomas also failed to label for that determinant. However, the presence of mp53-immunolabeling in a melanocytic proliferation-even if at low levels-should conversely prompt careful consideration of melanoma as the favored diagnosis in the confined setting of morphologically difficult cases, inasmuch as no example of CN or SN in this series had that characteristic.

Morphologic mimicry among human malignant neoplasms is a well-known phenomenon in surgical pathology; both undifferentiated and "committed" neoplasms may exhibit this trait. One particularly common group of histologic simulants includes ductal carcinomas of the breasts, the cutaneous appendages, and the salivary glands. One hundred three tumors in this structural cluster were analyzed microscopically and immunohistologically to codify points of potential pathologic similarity and difference. All the lesions were typified by irregularly permeative clusters and cords of atypical polygonal cells with variable luminal differentiation. A proportion of primary neoplasms in each site demonstrated in situ ductal components; in the absence of the latter elements, however, it was not possible to make topography-related morphologic distinctions among them. Immunostains for gross cystic disease fluid protein-15 (GCDFP-15), carcinoembryonic antigen, S100 protein, c-erbB-2 oncoprotein, estrogen receptor protein, and progesterone receptor protein also showed largely overlapping phenotypes in each of the three tumor categories, with selected exceptions. These differences were elucidated through paired chi 2 analysis and included a statistically significant infrequency of GCDFP-15 in eccrine sweat gland carcinomas, a paucity of carcinoembryonic antigen in breast cancers, and an absence of estrogen receptor protein in salivary duct carcinomas. Such findings may be useful in predefined differential diagnostic settings involving the distinction between primary and metastatic ductal cancers of the breasts, skin, and salivary glands. Nevertheless, because of the striking homologies between such tumors at structural and protein-synthetic levels of comparison, it is mandatory that all available clinicopathologic information be used in this context.

Determination of the biologic potential of cutaneous lymphoid infiltrates may be difficult by standard histologic or immunohistologic examination. The polymerase chain reaction (PCR) has been used to document clonal rearrangements of the immunoglobulin heavy chain gene in paraffin-embedded fixed tissues. To explore the value of PCR in evaluation of cutaneous lymphoid infiltrates, 93 archival nonmycotic lymphoid lesions (28 small or mixed lymphocytic lymphomas, 15 large cell lymphomas, 40 benign infiltrates, and 10 with atypical features) were analyzed. These cases had been previously immunophenotyped on paraffin sections, and clinical follow-up from 7 to 20 years was gathered. DNA products were generated using a seminested PCR technique, separated by 5% polyacrylamide gel electrophoresis, stained with ethidium bromide, and visualized under UV light Cases with a 100- to 120-base pair band were scored as positive. Of the 28 small or mixed cell lymphomas, 23 had a B-cell immunophenotype or consisted of a mixture of B and T cells; of these, seven (30%) demonstrated a monoclonal pattern, and three (13%) were indeterminate. Twelve large cell cases were B-cell or mixed; five (42%) of these were positive for a monoclonal band, while four (33%) were indeterminate. None of five T-cell small cell or three T-cell large cell lymphomas demonstrated a monoclonal band. In contrast, 39 of the 40 benign cases were T-cell predominant or mixed lesions. Nevertheless, 18 of these 40 cases on initial testing suggested possible monoclonality. Six were indeterminate, and 12 demonstrated apparent monoclonal bands, of which four were reproducible on repeat testing. No histologic or clinical features of lymphoma were present in 17 of these 18 cases, suggesting that they represent false-positive results. Most of the latter lesions showed sparse perivascular infiltrates, with very few B cells. This suggests that amplification of the immunoglobulin heavy chain gene from a small number of lymphocytes may produce a monoclonal band. In summary PCR may provide adjunct information about clonality in selected lymphoid skin lesions, but is rather insensitive in this setting. Such data must be carefully considered in the context of the histologic, immunohistologic, and clinical findings, particularly when assessing sparse infiltrates, because of the potential for false-positive results.

Sarcomatoid carcinomas (SC) of the lung are the most common pulmonary neoplasms that exhibit a composition by spindled or pleomorphic tumor cells. As such, many of them may be confused easily with true sarcomas diagnostically unless special immunohistological or ultrastructural analyses are performed. Reactivity is expected for keratin, epithelial membrane antigen, or collagen type IV in the sarcomalike elements in SC, although it may be focal. Electron microscopy often shows the presence of junctional complexes between tumor cells, with or without pericellular basal lamina and cytoplasmic skeins of intermediate filaments. Current terminological preferences are such that several formerly used terms--including "spindle-cell carcinoma," "pulmonary blastoma," "squamous cell carcinoma with pseudosarcomatous stroma," "pseudosarcoma," and "carcinosarcoma"--are now encompassed by the more generic designation of "sarcomatoid carcinoma." The clinical course of patients with this neoplasm is aggressive, with an overall 5-year survival rate approximating 20%.

BACKGROUND We recently demonstrated that inhibition of inducible nitric oxide synthase (iNOS) ameliorated severe acute lung allograft rejection. This study used a rat lung transplant model to determine (1) the time course and cellular localization of iNOS expression during the histological progression of unmodified acute rejection and (2) whether inhibition of iNOS prevented impaired gas exchange function of the allograft lung and/or ameliorated the histological changes of acute rejection. METHODS AND RESULTS iNOS mRNA and enzyme activity were expressed in allograft lungs during mild, moderate, and severe acute rejection, but not in normal, isograft, or allograft lungs before histological changes of mild acute rejection. iNOS expression in allografts resulted in elevated serum nitrite/nitrate levels, indicative of increased in vivo nitric oxide (NO) production. In situ hybridization demonstrated iNOS mRNA expression in infiltrating inflammatory cells, but not in allograft parenchymal cells. Allografts had significantly impaired gas exchange, which was prevented with the selective iNOS inhibitor aminoguanidine (PaO2 of 566+/-19, 76+/-22, and 504+/-105 mmHg for isograft, allograft, and aminoguanidine-treated allograft, respectively; P