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* Context.--The pathologic diagnosis of usual interstitial pneumonia (UIP) remains a challenging area, and application of histologic UIP guidelines has proved difficult. Objective.--To understand current practice approaches by pulmonary pathologists for the histologic diagnosis of UIP and other fibrotic interstitial lung diseases (ILDs). Design.--The Pulmonary Pathology Society (PPS) ILD Working Group developed and sent a 5-part survey on fibrotic ILD electronically to the PPS membership. Results.--One hundred sixty-one completed surveys were analyzed. Of the respondents, 89% reported using published histologic features in clinical guidelines for idiopathic pulmonary fibrosis (IPF) in their pathologic diagnosis; however, there was variability in reporting terminology, quantity and quality of histologic features, and the use of guideline categorization. Respondents were very likely to have access to pulmonary pathology colleagues (79%), pulmonologists (98%), and radiologists (94%) to discuss cases. Half of respondents reported they may alter their pathologic diagnosis based on additional clinical and radiologic history if it is pertinent. Airway-centered fibrosis, granulomas, and types of inflammatory infiltrates were considered important, but there was poor agreement on how these features are defined. Conclusions.--There is significant consensus among the PPS membership on the importance of histologic guidelines/features of UIP. There are unmet needs for (1) consensus and standardization of diagnostic terminology and incorporation of recommended histopathologic categories from the clinical IPF guidelines into pathology reports, (2) agreement on how to incorporate into the report relevant clinical and radiographic information, and (3) defining the quantity and quality of features needed to suggest alternative diagnoses. (Arch Pathol Lab Med. 2024;148:168-177; doi: 10.5858/arpa.2022-0530-OA), The histologic features of usual interstitial pneumonia (UIP), the fibrotic interstitial lung disease (ILD) pattern seen in, but not limited to, clinical idiopathic pulmonary fibrosis (IPF), was first described by [...]

* Context.--Transbronchial cryobiopsy is an emerging procedure to obtain lung tissue for diagnosis of interstitial lung disease and has gained popularity because it is less invasive and has a lower rate of complications compared with nonselective surgical lung biopsy. Objective.--To provide an overview of the status of the medical literature regarding transbronchial cryobiopsy. Data Sources.--A literature search was performed using PubMed search engine. The terms 'cryobiopsy' or 'cryo-probe' and 'interstitial lung disease' or 'diffuse parenchymal lung disease' or 'pulmonary fibrosis' were used, with the search concluding at the end of November 2019. Conclusions.--While the diagnostic yield of transbronchial cryobiopsy is slightly lower than surgical lung biopsy, a growing amount of literature suggests that with a multidisciplinary approach cryobiopsy provides diagnostic and prognostic information approaching that of surgical lung biopsy with lower morbidity and mortality. doi: 10.5858/arpa.2020-0007-RA, Diffuse interstitial lung diseases (ILD) are a heterogeneous group that differ widely in their pathogenesis, clinicopathologic features, therapeutic options, and prognosis. In approximately 30% of ILD patients, the specific diagnosis [...]

* Context.--Accurate diagnosis of idiopathic pulmonary fibrosis (IPF) requires multidisciplinary diagnosis that includes clinical, radiologic, and often pathologic assessment. In 2018, the American Thoracic Society, European Respiratory Society, Japanese Respiratory Society, and the Latin American Thoracic Society (ATS/ERS/JRS/ALAT) and the Fleischner Society each published guidelines for the diagnosis of IPF, which include criteria for 4 categories of confidence of a histologic usual interstitial pneumonia (UIP) pattern. Objective.--To (1) identify the role of the guidelines in pathologic assessment of UIP; (2) analyze the 4 guideline categories, including potential areas of difficulty; and (3) determine steps the Pulmonary Pathology Society and the greater pulmonary pathology community can take to improve current guideline criteria and histopathologic diagnosis of interstitial lung disease. Data Sources.--Data were derived from the guidelines, published literature, and clinical experience. Conclusions.--Both guidelines provide pathologists with a tool to relay to the clinician the likelihood that a biopsy represents UIP, and serve as an adjunct, not a replacement, for traditional histologic diagnosis. There are multiple challenges with implementing the guidelines, including (1) lack of clarity on the quantity and quality of histologic findings required, (2) lack of recognition that histologic features cannot be assessed independently, and (3) lack of guidance on how pathologists should incorporate clinical and radiographic information. Current criteria for 'probable UIP' and 'indeterminate for UIP' hinder accurate reflection of the likelihood of IPF. These challenges highlight the need for further morphologic-based investigations in the field of pulmonary pathology. doi: 10.5858/arpa.2020-0052-RA, Idiopathic pulmonary fibrosis (IPF) is a chronic progressive fibrosing interstitial lung disease (ILD) associated with a histologic and/or radiographic pattern of usual interstitial pneumonia (UIP) and a prognosis similar to [...]

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.(Arch Pathol Lab Med. 2018;142:89-108; doi: 10.5858/arpa.2017-0124-RA), The pathologic diagnosis of malignant mesothelioma (MM) continues to evolve and be refined as more antibodies and molecular tests become available for general use. This is especially applicable to distinguishing [...]

ARTICLE CONTENTS INTRODUCTION I. THE END OF TOTAL HARM PUNITIVE DAMAGES II. PROCEDURE, SUBSTANCE, AND THE INADEQUACY OF WILLIAMS A. Was the Williams Court's Purported Reliance on Procedural Due Process [...], In Philip Morris USA v. Williams, the Supreme Court held that the Constitution does not permit the imposition of punitive damages to punish a defendant for harm caused to third parties. This Article critiques the reasoning, but seeks ultimately to vindicate the result, of that landmark decision. It argues that, although the Court's procedural due process analysis does not stand up to scrutiny, punitive damages as punishment for third-party harm do indeed violate procedural due process, but for reasons far more profound than those offered by the Court. To reach that conclusion, the Article confronts the most basic and fundamental questions about punitive damages--questions that the Supreme Court has studiously avoided for more than a century: what, exactly, is the purpose of punitive damages, and how is it constitutional to impose them as a form of punishment in a judicial proceeding without affording the defendant the protection of the Constitution's criminal procedural safeguards? The Article argues that punitive damages are properly conceptualized as a form of punishment for private wrongs: judicially sanctioned private revenge. As such, it makes both theoretical and doctrinal sense to impose them without affording the defendant criminal procedural protections, which are necessitated only for the punishment of public wrongs on behalf of society. When, however, courts employ punitive damages as a form of punishment for public wrongs, they become a substitute for the criminal law, which thus makes an intolerable end run around the Bill of Rights. For that reason, Williams was ultimately correct that punitive damages must be limited to punishment for the harm done to the individual plaintiff, not the harm done to the general public. This reasoning suggests that contrary to the emerging conventional wisdom, Williams does not stand in the way of the imposition of nonpunitive extracompensatory damages of the type favored by law and economics scholars as a means of forcing the defendant to internalize the costs of its behavior in order to achieve optimal deterrence.

Context.--Transbronchial cryobiopsy has recently been proposed as an alternative to surgical biopsy in the diagnosis of diffuse lung disease. Objective.--To familiarize pathologists with transbronchial cryobiopsy, including what it is, how it is performed, how it compares to other techniques of lung biopsy in diffuse lung disease, what are the technical issues relating to it, what the complications are, how cryobiopsies should be interpreted, and the clinical usefulness of cryobiopsy. Data Sources.--All the available literature on cryobiopsy in diffuse lung disease through May 2016, primarily in the last 5 years, was reviewed, and some unpublished data known to the authors were included. Conclusions.--Cryobiopsies are considerably larger than forceps biopsies and allow pattern recognition approaching that of a surgical lung biopsy in many cases. Artifacts associated with cryobiopsy are minimal. In comparison with surgical lung biopsies, the diagnosis rate with cryobiopsies is lower, in the neighborhood of 80%, versus higher than 90% for surgical lung biopsies. Cryobiopsy is proposed as an alternative to surgical lung biopsy and a technique that may appreciably decrease the number of patients who require surgical lung biopsy for diagnosis. This is important because the mortality from cryobiopsy is very small (0.1% to date) compared with surgical lung biopsy (1.7% for elective procedures and considerably higher for nonelective procedures). (Arch Pathol Lab Med. 2017; 141:891-900; doi: 10.5858/arpa.2016-0233-RA), Transbronchial cryobiopsies are now used at many centers around the world to assess patients with diffuse lung disease, (1-13) and this has implications for pathologists who will encounter them. WHAT [...]

* Context.--Amyloidosis is a heterogeneous group of diseases characterized by the deposition of congophilic amyloid fibrils in the extracellular matrix of tissues and organs. To date, 31 fibril proteins have been identified in humans, and it is now recommended that amyloidoses be named after these fibril proteins. Based on this classification scheme, the most common forms of amyloidosis include systemic AL (formerly primary), systemic AA (formerly secondary), systemic wild-type ATTR (formerly age-related or senile systemic), and systemic hereditary ATTR amyloidosis (formerly familial amyloid polyneuropathy). Three different clinicopathologic forms of amyloidosis can be seen in the lungs: diffuse alveolar-septal amyloidosis, nodular pulmonary amyloidosis, and tracheobronchial amyloidosis. Objective.--To clarify the relationship between the fibril protein-based amyloidosis classification system and the clinicopathologic forms of pulmonary amyloidosis and to provide a useful guide for diagnosing these entities for the practicing pathologist. Data Sources.--This is a narrative review based on PubMed searches and the authors' own experiences. Conclusions.--Diffuse alveolar-septal amyloidosis is usually caused by systemic AL amyloidosis, whereas nodular pulmonary amyloidosis and tracheobronchial amyloidosis usually represent localized AL amyloidosis. However, these generalized scenarios cannot always be applied to individual cases. Because the treatment options for amyloidosis are dependent on the fibril protein-based classifications and whether the process is systemic or localized, the workup of new clinically relevant cases should include amyloid subtyping (preferably with mass spectrometry-based proteomic analysis) and further clinical investigation. (Arch Pathol Lab Med. 2017;141:247-254; doi: 10.5858/arpa.2016-0102-RA), The term amyloid (starchlike) was introduced into the medical literature by Rudolph Virchow in 1854, when he made the observation that corpora amylacea in the brain stained similarly to starch, [...]

Byline: Neil A. Abrahams (2), Thomas V. Colby (1), Richard H. Pearl (3), Bradley E. Chipps (4), Andrew L. Juris (4), Kevin O. Leslie (1) Keywords: Key words: pulmonary, hemangioma, pediatric, neoplasm, lung disease Abstract: Pulmonary hemangiomas are exceptionally rare in childhood and more so in infancy. They may involve the airways or the parenchyma, and may be localized or multifocal. We present two cases of pulmonary capillary hemangiomas. The first case is a localized form of capillary hemangioma that was resected from an 8-week-old infant with signs of respiratory distress. A computed tomography scan showed a cystic mass initially thought to be an intrapulmonary bronchogenic cyst. A segmental resection was performed and examination revealed a localized capillary hemangioma without cystic or cavernous features. The second case is an example of a multifocal capillary hemangioma from a 9-year-old child who presented clinically with clubbing of fingers and toes and radiologically had multiple discrete nodules localized to the right lung. The clinical and pathological features of the cases are discussed together with a review of the literature. The distinction from other vascular neoplasms of childhood is briefly described. Although rare, pulmonary hemangiomas should be entertained in the diagnosis of both solid and cystic intrapulmonary lesions of childhood and infancy. Author Affiliation: (1) Department of Anatomic Pathology, Mayo Clinic Scottsdale, 13400 E. Shea Boulevard, Scottsdale, AZ 85259, USA , US (2) Department of Anatomic Pathology, Cleveland Clinic Foundation L-2 5, 9500 Euclid Avenue, Cleveland, OH 44195, USA , US (3) Department of Surgery, Children's Hospital of Illinois, University of Illinois College of Medicine, 420 NE Glen Oak Avenue, Peoria, IL 61603, USA , US (4) Department of Pulmonary Medicine and Pediatric Cardiology, Sutter Medical Center, 5609 J Street, Suite C &amp AB, Sacramento, CA 95819, USA , US Article note: Received September 6, 2001 accepted November 13, 2001.

Langerhans'-cell histiocytosis is a disease characterized by a proliferation of cells called Langerhans cells. These are immune system cells and the proliferation can cause cell deposits in various organs. The exact cause of the proliferation is not known, but cigarette smoke is known to cause Langerhans cells to accumulate in the lungs. About 90% of patients with Langerhans'-cell histiocytosis in the lungs are smokers. The symptoms may resemble cancer. Bronchoalveolar lavage or lung biopsy can confirm the diagnosis. Smoking cessation should always be recommended, and corticosteroids and some chemotherapy drugs may be beneficial.

Inosine monophosphate dehydrogenase (IMPDH) controls a key metabolic step in the regulation of cell growth and differentiation. This step is the NAD-dependent oxidation of inosine 5[prime] monophosphate (IMP) to xanthosine 5[prime] monophosphate, the rate-limiting step in the synthesis of the guanine nucleotides. Two isoforms of IMPDH have been identified, one of which (type II) is significantly up- regulated in neoplastic and differentiating cells. As such, it has been identified as a major target in antitumor and immunosuppressive drug design. We present here the 2.9-[Angstrom] structure of a ternary complex of the human type II isoform of IMPDH. The complex contains the substrate analogue 6-chloropurine riboside 5[prime]-monophosphate (6-Cl-IMP) and the NAD analogue selenazole-4-carboxamide adenine dinucleotide, the selenium derivative of the active metabolite of the antitumor drug tiazofurin. The enzyme forms a homotetramer, with the dinucleotide binding at the monomer-monomer interface. The 6 chloro-substituted purine base is dehalogenated, forming a covalent adduct at C6 with Cys-331. The dinucleotide selenazole base is stacked against the 6-Cl-IMP purine ring in an orientation consistent with the B-side stereochemistry of hydride transfer seen with NAD. The adenosine end of the ligand interacts with residues not conserved between the type I and type II isoforms, suggesting strategies for the design of isoform-specific agents.

Horse liver alcohol dehydrogenase (LADH) catalyzes the first/rate-limiting step in alcohol metabolism that involves the oxidation of alcohol to aldehyde. The crystal structures of ternary complexes of the LADH active site single mutants F93W and V203A were scrutinized to explore the link between active site structure, enzyme conformation and catalytic hydride transfer step. Results indicate that the V203A/F93W double mutant LADH exhibited a 75-fold reduction in catalytic efficiency relative to that of the native enzyme.

We present evidence that the size of an active site side chain may modulate the degree of hydrogen tunneling in an enzyme-catalyzed reaction. Primary and secondary [k.sub.H]/[k.sub.T] and [k.sub.D]/[k.sub.T] kinetic isotope effects have been measured for the oxidation of benzyl alcohol catalyzed by horse liver alcohol dehydrogenase at 25 [degrees] C. As reported in earlier studies, the relationship between secondary [k.sub.H]/[k.sub.T] and [k.sub.D]/[k.sub.T] isotope effects provides a sensitive probe for deviations from classical behavior. In the present work, catalytic efficiency and the extent of hydrogen tunneling have been correlated for the alcohol dehydrogenase-catalyzed hydride transfer among a group of site-directed mutants at position 203. Val-203 interacts with the opposite face of the cofactor NA[D.sup.+] from the alcohol substrate. The reduction in size of this residue is correlated with diminished tunneling and a two orders of magnitude decrease in catalytic efficiency. Comparison of the x-ray crystal structures of a ternary complex of a high-tunneling (Phe-93 [approaches] Trp) and a low-tunneling (Val-203 [approaches] Ala) mutant provides a structural basis for the observed effects, demonstrating an increase in the hydrogen transfer distance for the low-tunneling mutant. The Val-203 [approaches] Ala ternary complex crystal structure also shows a hyperclosed interdomain geometry relative to the wild-type and the Phe-93 [approaches] Trp mutant ternary complex structures. This demonstrates a flexibility in interdomain movement that could potentially narrow the distance between the donor and acceptor carbons in the native enzyme and may enhance the role of tunneling in the hydride transfer reaction.

Lymphangioleiomyomatosis (LAM) is a rare lung disease which involves a proliferation of the smooth muscle within the lungs. Because the condition seems to affect only premenopausal women, it is thought to involve estrogens. Since the condition is so uncommon, there have been no controlled studies of therapeutic methods and there is no consensus on the best mode of treatment for these patients. A review of 32 patients seen since 1976 reveals some frequent observations associated with the disease and dispels some common misconceptions about the condition. The diagnosis of LAM was delayed an average of 44 months from the time of the appearance of the first symptoms. This is not surprising, as one of the standard symptoms of the condition is pneumothorax. Spontaneous pneumothorax is much more common than LAM, and only a specialist is likely to recognize LAM early on. The suspicion that the condition is associated with estrogens has prompted the therapeutic removal of the ovaries; 16 patients were so treated in the present series. One patient continued to take estrogen against medical advice. None of the patients improved, four remained stable, and 11 deteriorated. This observation is in contrast with some previously reported cases. Similar observations were made among the nine patients taking the antiestrogen drug tamoxifen. None improved, three remained stable, and six deteriorated. The course of the disease was not altered among patients who underwent menopause. Rapid progression of the disease was observed only in the first years after diagnosis, and many patients lived over two decades of slow progression. Overall, the average survival of the patients in the present series was 8.5 years after diagnosis. At present, 78 percent of the 32 patients remain alive. (Consumer Summary produced by Reliance Medical Information, Inc.)

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 in the field contributed to this update. Reference material includes peer-reviewed publications and textbooks. Conclusions.--There was consensus opinion regarding (1) distinction of benign from malignant mesothelial proliferations (both epithelioid and spindle cell lesions), (2) cytologic diagnosis of MM, (3) key histologic features of pleural and peritoneal MM, (4) use of histochemical and immunohistochemical stains in the diagnosis and differential diagnosis of MM, (5) differentiation of epithelioid MM from various carcinomas (lung, breast, ovarian, and colonic adenocarcinomas, and squamous cell and renal cell carcinomas), (6) diagnosis of sarcomatoid mesothelioma, (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 used is dependent on the differential diagnosis and on the antibodies available in a given laboratory. Immunohistochemical panels should contain both positive and negative markers. It is recommended that immunohistochemical markers 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 membranous markers). These guidelines are meant to be a practical reference for the pathologist. (Arch Pathol Lab Med. 2013;137:647-667; doi: 10.5858/arpa.2012-0214-OA), As part of the International Mesothelioma Interest Group (IMIG) biennial meeting held in Chicago (October 2006), there was a pathology half-day workshop that included invited lecturers and an open forum [...]

* Context.--Precise subtype diagnosis of non-small cell lung carcinoma is increasingly relevant, based on the availability of subtype-specific therapies, such as bevacizumab and pemetrexed, and based on the subtype-specific prevalence of activating epidermal growth factor receptor mutations. Objectives.--To establish a baseline measure of interobserver reproducibility for non-small cell lung carcinoma diagnoses with hematoxylin-eosin for the current 2004 World Health Organization classification, to estimate interobserver reproducibility for the therapeutically relevant squamous/nonsquamous subsets, and to examine characteristics that improve interobserver reproducibility. Design.--Primary, resected lung cancer specimens were converted to digital (virtual) slides. Based on a single hematoxylin-eosin virtual slide, pathologists were asked to assign a diagnosis using the 2004 World Health Organization classification. Kappa statistics were calculated for each pathologist-pair for each slide and were summarized by classification scheme, pulmonary pathology expertise, diagnostic confidence, and neoplastic grade. Results.--The 12 pulmonary pathology experts and the 12 community pathologists each independently diagnosed 48 to 96 single hematoxylin-eosin digital slides derived from 96 cases of non-small cell lung carcinoma resection. Overall agreement improved with simplification from the comprehensive 44 World Health Organization diagnoses (κ = 0.25) to their 10 major header subtypes (κ = 0.48) and improved again with simplification into the therapeutically relevant squamous/nonsquamous dichotomy (κ = 0.55). Multivariate analysis showed that higher diagnostic agreement was associated with better differentiation, better slide quality, higher diagnostic confidence, similar years of pathology experience, and pulmonary pathology expertise. Conclusions.--These data define the baseline diagnostic agreement for hematoxylin-eosin diagnosis of non-small cell lung carcinoma, allowing future studies to test for improved diagnostic agreement with reflex ancillary tests. (Arch Pathol Lab Med. 2013; 137:32-40; doi: 10.5858/arpa.2012-0033-OA), The diagnosis of non-small cell lung carcinoma (NSCLC) histologic subtype is the current gold standard for appropriate selection of chemotherapy, affecting the safety of bevacizumab (1) and the efficacy of [...]

Context.--Idiopathic interstitial pneumonias are a subset of diffuse pulmonary interstitial diseases classified by international consensus in 2002 as idiopathic pulmonary fibrosis, nonspecific interstitial pneumonia, cryptogenic organizing pneumonia, acute interstitial pneumonia, respiratory bronchiolitis interstitial lung disease, desquamative interstitial pneumonia, and lymphoid interstitial pneumonia. Each is associated with a characteristic histopathologic pattern. In 2011, updated consensus guidelines were released for diagnosis and management of idiopathic pulmonary fibrosis. The entire group of idiopathic interstitial pneumonias is currently undergoing refinement, with updates expected in a forthcoming consensus classification. Many of these recent and anticipated changes are relevant to pathologists. Objectives.--To review international consensus guidelines for diagnosis of idiopathic pulmonary fibrosis and other idiopathic interstitial pneumonias and to discuss recent and expected future classification updates. Data Sources.--Published peer-reviewed literature and personal experience of the authors. Conclusions.--Diagnosis of idiopathic interstitial pneumonias by multidisciplinary discussion among clinicians, radiologists, and pathologists is now strongly encouraged. Diagnosis of idiopathic pulmonary fibrosis no longer requires surgical lung biopsy; high-resolution computed tomography is an acceptable surrogate. In the context of clinical trials, pathologists are being asked to assign levels of confidence for histologic diagnosis of usual interstitial pneumonia in patients with idiopathic pulmonary fibrosis. Acute exacerbation of idiopathic pulmonary fibrosis is now accepted and should be considered when acute lung injury is superimposed on a background of usual interstitial pneumonia. The updated classification of idiopathic interstitial pneumonias will include a separate category for rare entities, including lymphoid interstitial pneumonia and idiopathic pleuroparenchymal fibroelastosis. (Arch Pathol Lab Med. 2012;136:1234-1241; doi: 10.5858/arpa.2012-0225-RA), The interstitial lung diseases comprise a group of diffuse pulmonary parenchymal diseases that are classified together because of similar clinical, radiologic, physiologic, and/or pathologic manifestations. Classically, these conditions show infiltrates [...]

* Context.--Malignant mesothelioma (MM) is an uncommon tumor that can be difficult to diagnose. Objective.--To develop practical guidelines for the pathologic diagnosis of MM. Data Sources.--A pathology panel was convened at the International Mesothelioma Interest Group biennial meeting (October 2006). Pathologists with an interest in the field also contributed after the meeting. Conclusions.--There was consensus opinion regarding (1) distinguishing benign from malignant mesothelial proliferations (both epithelioid and spindle cell lesions), (2) cytologic diagnosis of MM, (3) 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 mesothelioma, (7) use of molecular markers in the differential 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 used is dependent on the differential diagnosis and on the antibodies available in a given laboratory. Immunohistochemical panels should contain both positive and negative markers. The International Mesothelioma Interest Group recommends that markers 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 membranous markers). These guidelines are meant to be a practical reference for the pathologist. (Arch Pathol Lab Med. 2009;133:1317-1331), As part of the International Mesothelioma Interest Group biennial meeting held in Chicago (October 2006), there was a pathology half-day workshop that included invited lecturers and an open forum on [...]