Clinically Occult Diffuse Pleural Mesothelioma in Patients Presenting With Spontaneous Pneumothorax.

OBJECTIVES: To report histologic features of unsuspected diffuse pleural mesothelioma (DPM) in surgical specimens for pneumothorax and demonstrate how ancillary markers support a diagnosis of malignancy in this context. We explored whether pneumothorax may be a clinical manifestation of mesothelioma in situ (MIS). METHODS: A single-institution database search identified patients who underwent surgical resection for spontaneous pneumothorax (n = 229) and/or were diagnosed with DPM (n = 88) from 2000 to 2020. RESULTS: Spontaneous pneumothorax without clinical, radiologic, or intraoperative suspicion of mesothelioma was the initial presentation in 2 (2.3%) of 88 patients diagnosed with DPM. This represented 0.9% (2/229) of all patients undergoing surgical management of pneumothorax but accounted for a larger proportion of older patients (12.5% older than 70 years). Immunohistochemistry for BAP-1 and/or MTAP confirmed the diagnosis of DPM in 2 cases. Mesothelioma in situ was identified retrospectively by immunohistochemistry in 1 case of spontaneous pneumothorax from a 77-year-old man who developed invasive DPM 25 months later. No additional cases of MIS were identified in 19 surgical lung resections for spontaneous pneumothorax. CONCLUSIONS: Histologic examination of bleb resections with ancillary testing for cases with ambiguous features is essential for detection of early DPM. It is uncertain whether spontaneous pneumothorax may represent a clinical manifestation of MIS.

Usual Interstitial Pneumonia is the Most Common Finding in Surgical Lung Biopsies from Patients with Persistent Interstitial Lung Disease Following Infection with SARS-CoV-2.

BACKGROUND: There is increasing interest in persistent interstitial lung disease (ILD) following resolution of acute COVID-19. No studies have yet reported findings in surgical lung biopsies (SLB) from this patient population. METHODS: Our Michigan Medicine pathology database was queried for SLB reviewed between January 2020 and April 2021 from patients with persistent ILD following recovery from acute COVID-19. Slides for our retrospective observational study were independently reviewed by two thoracic pathologists, who were blinded to patient clinical data, radiographic findings, and previous pathologic diagnosis. FINDINGS: Eighteen cases met inclusion criteria. Of these, nine had usual interstitial pneumonia (UIP). These included two patients with superimposed acute lung injury (ALI). Five cases showed a spectrum of ALI that ranged from persistent diffuse alveolar damage to organizing pneumonia. Four patients had desquamative interstitial pneumonia (1), acute and organizing bronchopneumonia (1), or no diagnostic abnormality (2). Compared to patients without UIP, those with UIP tended to be older and have pre-existing lung disease prior to COVID-19. In patients with UIP, pre-SLB chest computed tomography changes included groundglass with interstitial thickening or peripheral reticulations with bronchiectasis; no UIP patients had groundglass only. The most common radiographic finding in patients without UIP was groundglass opacities only. INTERPRETATION: UIP was the most common pathologic finding in patients undergoing evaluation for post-COVID-19 ILD. Our preliminary data suggests that CT changes described as interstitial thickening, peripheral reticulations, and/or bronchiectasis may be helpful in identifying patients with underlying fibrotic chronic interstitial pneumonia for which UIP is the chief concern. FUNDING: No intramural or extramural funding sources supported this work.

Interstitial lung disease pathology in systemic sclerosis.

Interstitial lung disease is a relatively frequent manifestation of systemic sclerosis with approximately one-third of patients developing clinical restrictive lung disease. Fibrotic nonspecific interstitial pneumonia is the most common cause of diffuse parenchymal lung disease in patients with systemic sclerosis-associated interstitial lung disease (SSc-ILD), followed by usual interstitial pneumonia (UIP). Radiographic pleuroparenchymal fibroelastosis-like changes may accompany other forms of interstitial lung disease, most commonly UIP. In an appropriate clinical setting with supportive high-resolution computed tomography findings, lung biopsy is not needed to confirm the presence of interstitial lung disease and surgical lung biopsies are often reserved for atypical presentations. In this review, we discuss the histological findings that define the most common patterns of SSc-ILD and outline other findings sometimes encountered in lung biopsies obtained from systemic sclerosis patients, including pulmonary vascular changes, aspiration, chronic pleuritis, and diffuse alveolar damage.

A novel swine model of the acute respiratory distress syndrome using clinically relevant injury exposures.

To date, existing animal models of the acute respiratory distress syndrome (ARDS) have failed to translate preclinical discoveries into effective pharmacotherapy or diagnostic biomarkers. To address this translational gap, we developed a high-fidelity swine model of ARDS utilizing clinically relevant lung injury exposures. Fourteen male swine were anesthetized, mechanically ventilated, and surgically instrumented for hemodynamic monitoring, blood, and tissue sampling. Animals were allocated to one of three groups: (1) Indirect lung injury only: animals were inoculated by direct injection of Escherichia coli into the kidney parenchyma, provoking systemic inflammation and distributive shock physiology; (2) Direct lung injury only: animals received volutrauma, hyperoxia, and bronchoscope-delivered gastric particles; (3) Combined indirect and direct lung injury: animals were administered both above-described indirect and direct lung injury exposures. Animals were monitored for up to 12 h, with serial collection of physiologic data, blood samples, and radiographic imaging. Lung tissue was acquired postmortem for pathological examination. In contrast to indirect lung injury only and direct lung injury only groups, animals in the combined indirect and direct lung injury group exhibited all of the physiological, radiographic, and histopathologic hallmarks of human ARDS: impaired gas exchange (mean PaO2 /FiO2 ratio 124.8 ± 63.8), diffuse bilateral opacities on chest radiographs, and extensive pathologic evidence of diffuse alveolar damage. Our novel porcine model of ARDS, built on clinically relevant lung injury exposures, faithfully recapitulates the physiologic, radiographic, and histopathologic features of human ARDS and fills a crucial gap in the translational study of human lung injury.

Utility of CDC Screening Guidelines and Autopsy Findings in Identifying Decedents Who Die of SARS-CoV-2 Infection.

ABSTRACT: We assess the utility of a Centers for Disease Control and Prevention (CDC) guidelines-based coronavirus disease 2019 (COVID-19) screening checklist for postmortem severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) surveillance, detailing the relationship between the histologic findings at autopsy and attribution of death to COVID-19.SARS-CoV-2 nasopharyngeal swabs were collected at the time of autopsy in all "checklist-positive" decedents. Additional "checklist-negative" decedents were randomly tested daily. Lung slides were blindly reviewed by 3 pathologists, assessing for the presence of diffuse alveolar damage (DAD) and other findings. Sixteen decedents had positive postmortem SARS-CoV-2 nasopharyngeal swabs and underwent complete autopsies. Seven decedents had positive screening checklists. Of these, 4 had DAD and 1 had COVID-19-associated thromboembolic disease. Of the 9 decedents with negative screening checklists, 2 had DAD, but only 1 was attributed to COVID-19; the other was likely drug related. Acute bronchopneumonia was the second most common finding, and aspiration was the likely etiology in cases without concomitant DAD. COVID-19-related DAD was identified more commonly in decedents who screened positive by CDC checklist, but false-negatives did occur. Medical examiner offices should maintain a low threshold for random testing of decedents even when COVID-19 is not suspected.

Cytologic findings in effusions from patients with SARS-CoV-2 infection.

INTRODUCTION: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is associated with "flu-like" upper respiratory tract symptoms and pneumonia. Body cavity effusions develop in a subset of patients with advanced disease. Although SARS-CoV-2 is known to be present in certain body fluids (eg, blood) of COVID patients, it remains unclear if body cavity fluids are sites of infection. Our aim was to characterize the cytologic and clinical findings in COVID-19 patients with effusions. MATERIALS AND METHODS: A record search for all cases of body cavity effusion cytology in SARS-CoV-2 positive patients from March 1, 2020, to September 1, 2020, was performed. Clinical history, fluid chemical analysis, cytologic findings, and patient outcomes were recorded. All cytology slides were reviewed. In situ hybridization (ISH) targeting SARS-CoV-2 spike protein transcript (V-nCoV2019-S) was performed on cell block material in all cases. RESULTS: A total of 17 effusion cytology cases were identified among 15 COVID patients, including 13 pleural, 2 pericardial, and 2 peritoneal. Most (13 of 15) patients were hospitalized for COVID complications. Eight patients died during hospitalization, 7 from COVID complications. All fluids were transudative by protein criteria. Lymphocytic or histiocytic inflammation predominated in 12 of 17 cases. Five exhibited hemophagocytosis. No viral cytopathic changes or extra-medullary megakaryocytes were seen. Viral RNA was not detected in any case by ISH. CONCLUSIONS: Body cavity effusion is an ominous finding in patients with advanced COVID-19 disease. Such effusions tend to be transudative with lymphohistiocytic inflammation, and commonly exhibit hemophagocytosis, an otherwise rare finding in effusion cytologies. No direct infection of cellular elements by SARS-CoV-2 was identified by ISH.

Severe Acute Respiratory Syndrome Coronavirus 2 Surveillance in Decedents in a Large, Urban Medical Examiner's Office.

BACKGROUND: Given the challenges in implementing widespread testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), there is increasing interest in alternative surveillance strategies. METHODS: We tested nasopharyngeal swabs from 1094 decedents in the Wayne County Medical Examiner's Office for SARS-CoV-2. All decedents were assessed using a coronavirus disease 2019 (COVID-19) checklist, and decedents flagged using the checklist (298) were preferentially tested. A random sample of decedents not flagged using the checklist were also tested (796). We statistically analyzed the characteristics of decedents (age, sex, race, and manner of death), differentiating between those flagged using the checklist and not and between those SARS-CoV-2-positive and not. RESULTS: A larger percentage of decedents overall were male (70% vs 48%) and black (55% vs 36%) compared with the catchment population. Seven-day average percent positivity among flagged decedents closely matched the trajectory of percent positivity in the catchment population, particularly during the peak of the outbreak (March and April 2020). After a lull in May to mid-June, new positive tests in late June coincided with increased case detection in the catchment. We found large racial disparities in test results; SARS-CoV-2-positive decedents were substantially more likely to be black than SARS-CoV-2-negative decedents (82% vs 51%). SARS-CoV-2-positive decedents were also more likely to be older and to have died of natural causes, including of COVID-19 disease. CONCLUSIONS: Disease surveillance through medical examiners and coroners could supplement other forms of surveillance and serve as a possible early outbreak warning sign.

A comprehensive assessment of multi-system responses to a renal inoculation of uropathogenic E. coli in swine.

BACKGROUND: The systemic responses to infection and its progression to sepsis remains poorly understood. Progress in the field has been stifled by the shortcomings of experimental models which include poor replication of the human condition. To address these challenges, we developed and piloted a novel large animal model of severe infection that is capable of generating multi-system clinically relevant data. METHODS: Male swine (n = 5) were anesthetized, mechanically ventilated, and surgically instrumented for continuous hemodynamic monitoring and serial blood sampling. Animals were inoculated with uropathogenic E. coli by direct injection into the renal parenchyma and were maintained until a priori endpoints were met. The natural history of the infection was studied. Animals were not resuscitated. Multi-system data were collected hourly to 6 hours; all animals were euthanized at predetermined physiologic endpoints. RESULTS: Core body temperature progressively increased from mean (SD) 37.9(0.8)°C at baseline to 43.0(1.2)°C at experiment termination (p = 0.006). Mean arterial pressure did not begin to decline until 6h post inoculation, dropping from 86(9) mmHg at baseline to 28(5) mmHg (p = 0.005) at termination. Blood glucose progressively declined but lactate levels did not elevate until the last hours of the experiment. There were also temporal changes in whole blood concentrations of a number of metabolites including increases in the catecholamine precursors, tyrosine (p = 0.005) and phenylalanine (p = 0.005). Lung, liver, and kidney function parameters worsened as infection progressed and at study termination there was histopathological evidence of injury in these end-organs. CONCLUSION: We demonstrate a versatile, multi-system, longitudinal, swine model of infection that could be used to further our understanding of the mechanisms that underlie infection-induced multi-organ dysfunction and failure, optimize resuscitation protocols and test therapeutic interventions. Such a model could improve translation of findings from the bench to the bedside, circumventing a significant obstacle in sepsis research.

Lung and gut microbiota are altered by hyperoxia and contribute to oxygen-induced lung injury in mice.

Inhaled oxygen, although commonly administered to patients with respiratory disease, causes severe lung injury in animals and is associated with poor clinical outcomes in humans. The relationship between hyperoxia, lung and gut microbiota, and lung injury is unknown. Here, we show that hyperoxia conferred a selective relative growth advantage on oxygen-tolerant respiratory microbial species (e.g., Staphylococcus aureus) as demonstrated by an observational study of critically ill patients receiving mechanical ventilation and experiments using neonatal and adult mouse models. During exposure of mice to hyperoxia, both lung and gut bacterial communities were altered, and these communities contributed to oxygen-induced lung injury. Disruption of lung and gut microbiota preceded lung injury, and variation in microbial communities correlated with variation in lung inflammation. Germ-free mice were protected from oxygen-induced lung injury, and systemic antibiotic treatment selectively modulated the severity of oxygen-induced lung injury in conventionally housed animals. These results suggest that inhaled oxygen may alter lung and gut microbial communities and that these communities could contribute to lung injury.

A 53-Year-Old Woman With Dyspnea, Wheezing, and Irreversible Airway Obstruction.

CASE PRESENTATION: A previously healthy 53-year-old woman with 4 months of dyspnea and subjective wheezing presented to pulmonary clinic for a second opinion. Her medical history included hypertension, obesity, and OSA. She had been hospitalized 3 months prior at an outside hospital for evaluation of these symptoms. She had never smoked. She was a retired teacher and previously served as a pet nanny to dogs and cats. She denied antecedent respiratory infection or environmental exposure before the onset of her symptoms. Current medications included budesonide-formoterol, tiotropium, loratadine, and montelukast. She did not experience significant change in symptoms with bronchodilators or corticosteroid treatment.

Diffuse alveolar damage (DAD) resulting from coronavirus disease 2019 Infection is Morphologically Indistinguishable from Other Causes of DAD.

AIMS: Diffuse alveolar damage (DAD) is a ubiquitous finding in inpatient coronavirus disease 2019 (COVID-19)-related deaths, but recent reports have also described additional atypical findings, including vascular changes. An aim of this study was to assess lung autopsy findings in COVID-19 inpatients, and in untreated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive individuals who died in the community, in order to understand the relative impact of medical intervention on lung histology. Additionally, we aimed to investigate whether COVID-19 represents a unique histological variant of DAD by comparing the pathological findings with those of uninfected control patients. METHODS AND RESULTS: Lung sections from autopsy cases were reviewed by three pulmonary pathologists, including two who were blinded to patient cohort. The cohorts included four COVID-19 inpatients, four cases with postmortem SARS-CoV-2 diagnoses who died in the community, and eight SARS-CoV-2-negative control cases. DAD was present in all but one SARS-CoV-2-positive patient, who was asymptomatic and died in the community. Although SARS-CoV-2-positive patients were noted to have more focal perivascular inflammation/endothelialitis than control patients, there were no significant differences in the presence of hyaline membranes, fibrin thrombi, airspace organisation, and 'acute fibrinous and organising pneumonia'-like intra-alveolar fibrin deposition between the cohorts. Fibrinoid vessel wall necrosis, haemorrhage and capillaritis were not features of COVID-19-related DAD. CONCLUSIONS: DAD is the primary histological manifestation of severe lung disease in COVID-19 patients who die both in hospital and in the community, suggesting no contribution of hyperoxaemic mechanical ventilation to the histological changes. There are no distinctive morphological features with which to confidently differentiate COVID-19-related DAD from DAD due to other causes.

Postmortem Lung Findings in a Patient With Asthma and Coronavirus Disease 2019.

Asthma is increasingly recognized as an underlying risk factor for severe respiratory disease in patients with coronavirus disease 2019 (COVID-19), particularly in the United States. Here, we report the postmortem lung findings from a 37-year-old man with asthma, who met the clinical criteria for severe acute respiratory distress syndrome and died of COVID-19 less than 2 weeks after presentation to the hospital. His lungs showed mucus plugging and other histologic changes attributable to asthma, as well as early diffuse alveolar damage and a fibrinous pneumonia. The presence of diffuse alveolar damage is similar to descriptions of autopsy lung findings from patients with severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome coronavirus, and the absence of a neutrophil-rich acute bronchopneumonia differs from the histologic changes typical of influenza. The relative contribution of mucus plugging to his hypoxemia is unknown.

A challenging case of Mesenchymal Chondrosarcoma involving the thyroid and special considerations for diagnosis.

BACKGROUND: Thyroid ultrasound is usually used to risk-stratify incidental thyroid nodules. Nodules with high risk sonographic features for malignancy are evaluated by fine-needle aspiration. The role of core needle biopsy for thyroid nodules is limited to cases where the fine needle aspiration is inconclusive. CASE PRESENTATION: We describe a rare case of mesenchymal chondrosarcoma of the thyroid gland with uncertain primary origin. Thyroid ultrasound showed right sided large, solid, hypoechoic nodule with calcifications and peripheral vascularity and unremarkable isthmus and left thyroid lobe. Fine needle aspiration of the right nodule suggested lymphocytic thyroiditis. The sonographic findings contradicted the typical bilateral clinical and sonographic picture of lymphocytic thyroiditis. A core needle biopsy showed mesenchymal chondrosarcoma. CONCLUSION: This case highlights the importance of correlating pathologic diagnosis with sonographic findings, the appropriate utilization of fine needle aspiration and core needle biopsy to evaluate thyroid nodules and the rare incidence of mesenchymal chondrosarcoma involving the thyroid.

Diagnosis of Lung Carcinoma on Small Biopsy.

Given the growing desire in clinical practice to detect lung carcinoma early, small biopsies are becoming more common and vital to the diagnostic process. Accurately diagnosing lung carcinoma on small biopsies is challenging but can significantly affect patient management. The challenge is due in part to the overlapping features between benign, reactive, and malignant processes and the lack of discriminating biomarkers. Specimen preservation for ancillary tests is also increasingly important to provide targeted precision medicine. We focuses on the morphologic features and diagnostic pitfalls of the most common lung carcinoma seen in small biopsies and the appropriate specimen handling practice.