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Context.--The pathologic diagnosis of pulmonary extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) is challenging. Objective.--To evaluate the diagnostic usefulness and limitations of current diagnostic strategies for pulmonary MALT lymphoma. Design.--A retrospective review of 120 cases of pulmonary MALT lymphoma from 2014 through 2021 was performed. Results.--Clinicoradiologic presentations overlapped with previous observations in patients with MALT lymphoma, such as a wide age range, female predominance, frequent association with autoimmune disease or immunodeficiency, and broad imaging findings. The histopathologic diagnosis was based on a combination of morphology, immunohistochemistry, and demonstration of B-cell lineage clonality. Two-thirds (76 of 113) of MALT lymphomas had lympho-plasmacytoid cytomorphology. Occasionally, MALT lymphomas were associated with granulomas/giant cells (29%, 35 of 120) or immunoglobulin deposition disease (21%, 25 of 120), including light chain/heavy chain deposition disease, amyloidosis, and/or crystal storing histiocytosis. While CD5, CD10, Bcl-2, and Bcl-6 rarely revealed aberrancies, aberrant CD43 expression either on B-cells or on plasma cells was detected in 42% (27 of 64) of cases, including cases for which proof of clonality could not be obtained. [kappa]/[lambda] in situ hybridization was particularly useful for tumors with lymphoplasmacytoid morphology but performed poorly in lymphomas having no plasmacytic differentiation. [kappa]/[lambda] immunohistochemistry showed no additional usefulness when applied together with [kappa]/[lambda] in situ hybridization. Immunoglobulin gene rearrangement studies by polymerase chain reaction achieved high detection rates of clonality in all cytomorphologic subgroups. Conclusions.--Our study offers a practical evaluation of common diagnostic tests in pulmonary MALT lymphoma. We offer recommendations for a diagnostic workup that takes into consideration the usefulness and the specific limitations of the various diagnostic strategies. doi: 10.5858/arpa.2022-0521-OA, Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) represents the most common type of primary lymphoma of the lung. As at other anatomic sites, MALT lymphoma of the [...]

E-cigarette or vaping product use-associated lung injury (EVALI) is a severe pulmonary illness associated with the use of e-cigarettes or vaping products that was officially identified and named in 2019. This American Thoracic Society workshop was convened in 2021 to identify and prioritize research and regulatory needs to adequately respond to the EVALI outbreak and to prevent similar instances of disease associated with e-cigarette or vaping product use. An interdisciplinary group of 26 experts in adult and pediatric clinical care, public health, regulatory oversight, and toxicology were convened for the workshop. Four major topics were examined: 1) the public health and regulatory response to EVALI; 2) EVALI clinical care; 3) mechanisms contributing to EVALI; and 4) needed actions to address the health effects of EVALI. Oral presentations and group discussion were the primary modes used to identify top priorities for addressing EVALI. Initiatives including a national EVALI case registry and biorepository, integrated electronic medical record coding system, U.S. Food and Drug Administration regulation and enforcement of nicotine e-cigarette standards, regulatory authority over nontobacco-derived e-cigarettes, training in evaluating exogenous exposures, prospective clinical studies, standardized clinical follow-up assessments, ability to more readily study effects of cannabinoid e-cigarettes, and research to identify biomarkers of exposure and disease were identified as critical needs. These initiatives will require substantial federal investment as well as changes to regulatory policy. Overall, the workshop identified the need to address the root causes of EVALI to prevent future outbreaks. An integrated approach from multiple perspectives is required, including public health; clinical, basic, and translational research; regulators; and users of e-cigarettes. Improving the public health response to reduce the risk of another substantial disease-inducing event depends on coordinated actions to better understand the inhalational toxicity of these products, informing the public of the risks, and developing and enforcing regulatory standards for all e-cigarettes.

* Context.--Diffuse parenchymal lung disease (DPLD) is a well-recognized complication of systemic connective tissue disease (CTD) but rarely arises in patients with psoriasis or psoriatic arthritis, a poorly understood phenomenon. Objective.--To characterize DPLD associated with psoriasis or psoriatic arthritis, with or without prior immunomodulation. Design.--Pathology consultation files were searched for patients having psoriasis or psoriatic arthritis and DPLD. After excluding cases with active infection or smoking-related DPLD only, 44 patients (22 women; median age, 60 years; range, 23-81 years) were enrolled. Clinical history and pathology slides were reviewed. Results.--Twenty-seven of 44 patients (61 %) had psoriatic arthritis; the remainder had psoriasis alone. Most presented many years later with nonspecific respiratory symptoms. Nearly one-third had no prior immunosuppression, and most had no concomitant CTD. Radiographically, ground-glass opacities, consolidation, and/or reticulation were typical. Histologically, nonspecific interstitial pneumonia and unclassifiable fibrosis were seen in 24 patients (55%) and 8 patients (18%), respectively; usual interstitial pneumonia and airway-centered fibrosis were rare. Super-imposed acute lung injury was common, usually manifesting as organizing pneumonia. Lymphoplasmacytic infiltrates, lymphoid aggregates, and chronic pleuritis were frequent. Interstitial granulomas were seen in 17 patients (39%) but were usually rare, poorly formed, and non-necrotizing. No histologic differences were apparent among patients with or without concomitant CTDs or prior therapy. Conclusions.--Some patients with psoriasis or psoriatic arthritis develop clinically significant DPLD, even without prior therapy. Histopathologic findings mirror changes seen with other CTDs. Additional studies are warranted to clarify the association between psoriasis or psoriatic arthritis and DPLD. doi: 10.5858/arpa.2021-0616-OA, Psoriasis is a common chronic autoimmune inflammatory disorder of the skin that may exhibit a variety of clinical manifestations. Some cases of psoriasis are complicated by the development of psoriatic [...]

Context.--Studies of lungs in patients with COVID-19 have focused on early findings. Objective.--To systematically study histopathologic and imaging features and presence of SARS-CoV-2 RNA in lung tissue from patients in later stages of COVID-19. Design.--Autopsies, explants, surgical lung biopsies, transbronchial biopsies, cryobiopsies, and needle biopsies from patients with COVID-19 whose onset of symptoms/ confirmed diagnosis was more than 28 days before the procedure were studied. Available images were reviewed. Reverse transcription droplet digital polymerase chain reaction for SARS-CoV-2 RNA was performed on lung tissue. Results.--Of 44 specimens (43 patients; median age, 59.3 years; 26 [60.5%] male) features of acute lung injury (ALI) were seen in 39 (88.6%), predominantly organizing pneumonia and diffuse alveolar damage, up to 298 days after onset of COVID-19. Fibrotic changes were found in 33 specimens (75%), most commonly fibrotic diffuse alveolar damage (n = 22) and cicatricial organizing pneumonia (n = 12). Time between acquiring COVID-19 and specimen was shorter in patients with diffuse ALI (median, 61.5 days) compared with patients with focal (140 days) or no AlI (130 days) (P =.009). Sixteen (of 20; 80%) SARS-CoV-2 reverse transcription droplet digital polymerase chain reaction tests were positive, up to 174 days after COVID-19 onset. Time between COVID-19 onset and most recent computed tomography in patients with consolidation on imaging was shorter (median, 43.0 days) versus in patients without consolidation (87.5 days; P =.02). Reticulations were associated with longer time to computed tomography after COVID-19 onset (median, 82 versus 23.5 days; P =.006). Conclusions.--ALI and SARS-CoV-2 RNA can be detected in patients with COVID-19 for many months. ALI may evolve into fibrotic interstitial lung disease., Coronavirus disease 2019 (COVID-19) is a viral infection caused by SARS-CoV-2. More than 235 million people have been infected globally, with a death burden in excess of 4.8 million since [...]

Context.--Idiopathic pulmonary fibrosis is a clinical syndrome characterized by the presence of usual interstitial pneumonia (UIP) radiologically and pathologically. Per consensus criteria adopted in 2011, diagnosis of idiopathic pulmonary fibrosis no longer requires a biopsy in an appropriate context if UIP is seen on imaging. As a result, lung biopsies are now typically reserved for patients having indeterminate clinical or imaging findings or suspicion for alternative diagnoses, but the impact of updated guidelines on pathology practice remains unclear. Objective.--To determine the frequency of histologic UIP before and after 2011. Design.--Surgical lung biopsies from adults were studied within two 4-year periods: July 1, 2006 through June 30, 2010 and January 1, 2012 through December 31, 2015. Pathology slides were reviewed in a fashion blinded to clinical information and were classified using current guidelines. Results.--Biopsies from 177 and 86 patients (mean [SD] age, 62 [12] and 59 [14] years; 50.3% [89 of 177] and 48.8% [42 of 86] men) before and after 2011, respectively, were reviewed. Probable UIP or UIP was less-frequently encountered after 2011 in all patients with fibrosis (9 of 54 [16.7%] versus 41 of 119 [34.5%] before 2011, P = .02) and also in patients 50 years old and older (8 of 46 [17.4%] versus 39 of 109 [35.8%] before 2011, P = .02), with a concomitant rise in cases indeterminate for UIP or showing alternative diagnoses. Conclusions.--Histology for UIP is less frequently encountered in our contemporary practice compared with the historic era. The pretest probability of a non-UIP diagnosis is now high, even in elderly patients, underscoring the need for pathologists to be familiar with the histologic features of alternative diagnoses. (Arch Pathol Lab Med. 2021;145:717-727; doi: 10.5858/arpa.2020-0100-OA, Idiopathic pulmonary fibrosis (IPF) is a relentlessly progressive chronic fibrosing interstitial pneumonia of unknown cause, usually occurring in adults older than 50 years, with a poor prognosis and a median [...]

* Context.--Vaping is the inhalation of heated aerosol from a small battery-powered device as a method to deliver nicotine or other substances. A recent outbreak of severe respiratory illness primarily in the United States has put a spotlight on vaping and its potential risks. Objective.--To familiarize pathologists with vaping, the cytologic and histopathologic features of vaping-associated acute lung injury, and the role of pathology in this diagnosis. Data Sources.--A targeted literature review was performed. Conclusions.--Most cases of vaping-associated lung injury have been linked to vaping products containing tetrahydrocannabinol or other cannabinoids. Lung biopsies show a spectrum of nonspecific acute lung injury patterns (organizing pneumonia, diffuse alveolar damage, acute fibrinous, and organizing pneumonia, or combinations of the above), accompanied by prominent, foamy macrophage accumulation. Injury is usually accentuated around small airways. Lipid-laden macrophages can be identified in bronchioloalveolar lavage fluid in most patients and these can be highlighted using lipid stains, such as oil red O, but the clinical utility of this finding remains unclear, as lipid-laden macrophages can be seen in a wide variety of processes and should not be relied upon to make the diagnosis. Classic histologic features of exogenous lipoid pneumonia have not been identified in tissue samples. Lightly pigmented macrophages, similar to those seen with traditional cigarette smoking, are present in some cases but are usually a minor feature. To date, no specific pathologic features for vaping-related injury have been identified, and it remains a diagnosis of exclusion that requires clinic-pathologic correlation. doi: 10.5858/arpa.2020-0024-RA, WHAT IS VAPING? A PRIMER ON DEVICES, CONTENTS, AND TERMINOLOGY 'Vaping' is the inhalation of an aerosol (vapor) generated by heating a liquid in a small batterypowered device. (1-3) This [...]

* 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.--Hypersensitivity pneumonitis (HP) is a lung disease that develops in susceptible individuals after inhalational exposure to an organic antigen or chemical compound. Pathogenesis is attributed to a combination of type III (immune complex-mediated) and type IV (delayed) hypersensitivity reactions to the inciting agent.Objective.--To provide an overview of the current status of the medical literature regarding hypersensitivity pneumonitis.Data Sources.--A literature search was performed using PubMed and Google search engines. The terms 'hypersensitivity pneumonitis' and 'extrinsic allergic alveolitis' were used, with the search starting on January 9, 2017, and concluding March 8, 2017.Conclusions.--As a pathologist, it is important to consider hypersensitivity pneumonitis when examining lung specimens because it is often clinically and pathologically overlooked. Recognizing the often subtle findings and correlating them with the patient's history or suggesting a thorough clinical investigation of potential exposures can be of help in identifying the underlying condition so that the patient can be appropriately managed.(Arch Pathol Lab Med. 2018;142:120-126; doi: 10.5858/arpa.2017-0138-SA), Hypersensitivity pneumonitis (HP, also referred to as extrinsic allergic alveolitis in the medical literature) can develop after inhalational exposure to a particular antigen or chemical in a susceptible individual. Hypersensitivity [...]