The goal of the American Association of Bronchology and Interventional Pulmonology Essential Knowledge in Interventional Pulmonology Series is to provide clinicians with concise, up-to-date reviews of important topics in the field of interventional pulmonology. This 3-year alternating rotation of primary topics continues with the current discussion of selected concepts in bronchoscopic airway stenting. In this article, we update the reader on modern airway stenting practice in 3 parts: part 1- a data review of the therapeutic benefit of stenting in different clinical scenarios; part 2- an overview of stent-associated complications and initial postinsertion stent management; and part 3- new and evolving approaches to airway stenting. This review complements the Essential Knowledge in Interventional Pulmonology Lecture Series presented at the 2024 AABIP Annual Conference, available for viewing on the AABIP website (https://aabip.memberclicks.net/essential-knowledge-in-interventional-pulmonology-series).

The goal of the American Association of Bronchology and Interventional Pulmonology Essential Knowledge in Interventional Pulmonology Series is to provide clinicians with concise, up-to-date reviews of important topics in the field of interventional pulmonology. This 3-year alternating rotation of primary topics continues with the current discussion of selected concepts in bronchoscopic airway stenting. In this article, we update the reader on modern airway stenting practice in 3 parts: part 1- a data review of the therapeutic benefit of stenting in different clinical scenarios; part 2- an overview of stent-associated complications and initial postinsertion stent management; and part 3- new and evolving approaches to airway stenting. This review complements the Essential Knowledge in Interventional Pulmonology Lecture Series presented at the 2024 AABIP Annual Conference, available for viewing on the AABIP website (https://aabip.memberclicks.net/essential-knowledge-in-interventional-pulmonology-series).

The American Association of Bronchology and Interventional Pulmonology (AABIP) Essential Knowledge in Interventional Pulmonology Series aims to provide clinicians with concise, up-to-date reviews of key topics in the field, presented on a 3-year rotating cycle. The 2024 series focused on therapeutic bronchoscopy. In this article, we provide an update on curative-intent bronchoscopy for centrally located early-stage lung cancer, including a review of bronchoscopic imaging modalities for disease detection and current management techniques. These reviews are designed to complement the Essential Knowledge in Interventional Pulmonology Lecture Series delivered at the 2024 AABIP Annual Conference, which is available for viewing on the AABIP website: https://aabip.memberclicks.net/essential-knowledge-in-interventional-pulmonology-series.

The American Association of Bronchology and Interventional Pulmonology (AABIP) Essential Knowledge in Interventional Pulmonology Series aims to provide clinicians with concise, up-to-date reviews of key topics in the field, presented on a 3-year rotating cycle. The 2024 series focused on therapeutic bronchoscopy. In this article, we provide an update on curative-intent bronchoscopy for centrally located early-stage lung cancer, including a review of bronchoscopic imaging modalities for disease detection and current management techniques. These reviews are designed to complement the Essential Knowledge in Interventional Pulmonology Lecture Series delivered at the 2024 AABIP Annual Conference, which is available for viewing on the AABIP website: https://aabip.memberclicks.net/essential-knowledge-in-interventional-pulmonology-series

Purpose of review Biopsy tools have been essential in improving the diagnostic accuracy of bronchoscopic procedures. Of these tools, cryobiopsy has emerged as a promising technique for diagnosing thoracic diseases. This review summarizes the existing data comparing cryobiopsies to other mechanical biopsy methods for sampling endobronchial, parenchymal, and mediastinal targets. Recent findings Initially adopted for managing airway stenoses, the use of cryoprobes has expanded to diagnosing endobronchial lesions, parenchymal opacities, and mediastinal lymph node pathologies. Studies have demonstrated that cryobiopsy offers a higher diagnostic yield than forceps biopsy alone. By leveraging the Joule-Thomson effect to freeze and collect larger tissue samples compared to traditional methods, cryobiopsy improves diagnostic accuracy and helps in better characterizing the nature of the lesions. While the risk of complications, such as pneumothorax and hemorrhage are comparable to, or higher than traditional biopsy methods, cryobiopsy's enhanced diagnostic capabilities make it a valuable tool in the assessment of pulmonary disease. Summary Compared with other mechanical biopsy techniques, cryoprobe biopsies significantly enhance the diagnostic yield for endobronchial lesions, interstitial lung disease, pulmonary nodules, and mediastinal lymph nodes.

Supplementary Table S1. ALK inhibitors in clinical development. Supplementary Table S2. Summary of clinical characteristics of ALK-positive patients undergoing biopsies at the time of ALK inhibitor resistance. Supplementary Table S3. Paired, post-crizotinib and post second-generation ALK inhibitor biopsies. Supplementary Table S4. Treatment course of ALK-positive patients undergoing post-ceritinib biopsies. Supplementary Table S5. Treatment course of ALK-positive patients undergoing post-alectinib biopsies. Supplementary Table S6. Treatment course of ALK-positive patients undergoing post-brigatinib biopsies. Supplementary Table S7. Resistant biopsies with {greater than or equal to}2 resistance mutations. Supplementary Table S8. Mutations in ceritinib-resistant biopsies. Supplementary Table S9. Mutations in alectinib-resistant biopsies. Supplementary Table S10. Mutations in brigatinib-resistant biopsies. Supplementary Table S11. Single-nucleotide variants identified in patient-derived cell lines. Supplementary Table S12. EMT in ceritinib-resistant biopsies. Supplementary Table S13. Cells seeded for survival assays. Supplementary Table S14. Cells seeded for growth assays.

INTRODUCTION: Primary pulmonary mucoepidermoid carcinoma (MEC) is a rare, often low-grade, tumor of glandular origin1.Because of the usual polypoid structure and endobronchial location, patients typically present with recurrent postobstructive pneumonia2.Presentation with symptoms due to definitive paraneoplastic syndromes (PNS) has never been reported in primary pulmonary MEC.In the following report, we describe a suspected case of PNS due to endobronchial MEC wherein the patient presented with diplopia which resolved after tumor resection.CASE PRESENTATION: A 67-year-old healthy man presented to the emergency department at the advice of his ophthalmologist after developing bilateral horizontal diplopia three days prior.His vision changes were preceded by a two-week febrile illness with cough and pharyngitis that had resolved prior to presentation after treatment with amoxicillin.Physical examination demonstrated multiple cranial nerve palsies, most notable in the bilateral abducens nerves.Magnetic resonance imaging of the brain and orbits was unremarkable.Preliminary cerebrospinal fluid analysis showed non-specific elevated protein and immunoglobulin G levels.Concurrently, his recent respiratory symptoms prompted chest radiograph followed by computed tomography of the chest which revealed an endobronchial lesion in the right bronchus intermedius with distal obstructive atelectasis of the middle and lower lobes.The patient underwent flexible and rigid bronchoscopy with tumor biopsy, transbronchial nodal aspiration, and multimodal tumor debridement.Pathologic evaluation showed low-grade mucoepidermoid carcinoma without nodal involvement.The patient was discharged to await further treatment recommendations.During this time, additional CSF studies returned which detected an elevated level of AChR ganglionic neuronal antibodies (0.05nmol/L; ref <0.02nmol/L) supporting a paraneoplastic neurologic process as the cause of his cranial nerve deficits.After multidisciplinary discussion, right pneumonectomy was recommended to ensure complete resection.The day following uncomplicated pneumonectomy, the patient reported significant improvement in diplopia, and it completely resolved over the subsequent month.DISCUSSION: Although various primary lung cancers have been associated with antibody-mediated paraneoplastic syndromes affecting the nervous system, this association has never been reported with pulmonary mucoepidermoid carcinoma.It has been hypothesized that infection may trigger paraneoplastic syndromes, which may have been a factor in this case.Pulmonary MEC is typically low-grade and localized at the time of presentation and prompt diagnosis and surgical resection can be curative for both the malignancy and any associated paraneoplastic syndrome.CONCLUSIONS: This is the first reported case of antibody-mediated paraneoplastic syndrome affecting the nervous system associated with pulmonary mucoepidermoid carcinoma.Surgical resection of the tumor resulted in complete resolution of the associated cranial nerve deficits.

Supplementary Figure S1. ALK G1202R versus ALK G1202del. Supplementary Figure S2. ALK G1202del in ALK-rearranged lung cancer. Supplementary Figure S3. Swimmer's plot - alectinib. Supplementary Figure S4. Evaluation of MGH075-2E in drug screen. Supplementary Figure S5. MGH067-1 harbors an ALK rearrangement. Supplementary Figure S6. MGH021-5A. Supplementary Figure S7. MGH051-2C and MGH084-1D. Supplementary Figure S8. MGH049-1A and MGH075-2E. Supplementary Figure S9. MGH034-2A.

SESSION TITLE: Disorders of Pleura Case Report Posters 10 SESSION TYPE: Case Report Posters PRESENTED ON: 10/10/2023 09:40 am - 10:25 am INTRODUCTION: Laparoscopic surgery is a common modality for many different intra-peritoneal procedures. While rare, pulmonary complications such as capnothorax, can occur. Pleural effusions, and particularly the delayed presentation of pleural effusions, have been less well described. CASE PRESENTATION: A 49-year-old man with no prior pulmonary history underwent a robotic radical prostatectomy and left pelvic lymph node dissection for intermediate risk prostate cancer. There were no noted intra-operative complications and the patient was successfully extubated and brought to the recovery room. Post-operatively, he was noted to have pleuritic chest pain, facial swelling, and hypoxemia. A chest x-ray (CXR) revealed pneumoperitoneum, subcutaneous emphysema and bilateral pneumothoraces, thought to be secondary to carbon dioxide (CO2) insufflation during the procedure. He was treated conservatively with supplemental oxygen alone. Subsequent CXRs demonstrated stability and the patient was weaned off of supplemental oxygen prior to discharge on post-operative day 2. A CT scan 1 month later showed persistent moderate pneumoperitoneum, but resolution of bilateral pneumothoraces, as well as subcutaneous emphysema. He was found, however, to have bilateral (right greater than left) pleural effusions. Around 8 weeks after surgery, he presented to the ED with shortness of breath and underwent a right thoracentesis which revealed a neutrophil-predominant exudative effusion. Cultures and additional infectious serologies were negative, cytology was negative for malignancy and the CT scan did not reveal any pleural implants or obvious cause for the effusions. Additionally, autoimmune workup was negative. The bilateral effusions were monitored over several outpatient visits with resolution over then next several months. DISCUSSION: While CO2 insufflation has been known to cause bilateral pneumothoraces, most of which can be treated conservatively and without chest drainage, pleuritis and pleural effusions have been less frequently described. As alternative etiologies were ruled out, this patient's delayed presentation of pleuritis is thought to be post-laparoscopic capnothorax which should be noted as a rare complication of laparoscopic surgery. It has been proposed that longer surgery duration, increased insuffulation pressure and lower humidity and temperature can increase inflammation, mesothelial injury and oxidative stress in pneumoperitoneum, and this may suggest a mechanism for capnothorax related pleuritis. CONCLUSIONS: Intra-peritoneal CO2 insufflation is known to cause bilateral pneumothoraces. Patients should be monitored for pleuritis and pleural effusions that may occur after the resolution of capnothorax. REFERENCE #1: Umano GR, Delehaye G, Noviello C, Papparella A. The "Dark Side" of Pneumoperitoneum and Laparoscopy. Wang PH, ed. Minimally Invasive Surgery. 2021;2021:1-9. doi:10.1155/2021/5564745 DISCLOSURES: No relevant relationships by Jessica Channick No relevant relationships by Colleen Channick No relevant relationships by Miki Ueoka

Interventional pulmonary medicine has developed as a subspecialty focused on the management of patients with complex thoracic disease. Leveraging minimally invasive techniques, interventional pulmonologists diagnose and treat pathologies that previously required more invasive options such as surgery. By mitigating procedural risk, interventional pulmonologists have extended the reach of care to a wider pool of vulnerable patients who require therapy. Endoscopic innovations, including endobronchial ultrasound and robotic and electromagnetic bronchoscopy, have enhanced the ability to perform diagnostic procedures on an ambulatory basis. Therapeutic procedures for patients with symptomatic airway disease, pleural disease, and severe emphysema have provided the ability to palliate symptoms. The combination of medical and procedural expertise has made interventional pulmonologists an integral part of comprehensive care teams for patients with oncologic, airway, and pleural needs. This review surveys key areas in which interventional pulmonologists have impacted the care of thoracic disease through bronchoscopic intervention.

INTRODUCTION:Transbronchial lung cryobiopsy (TBLC) has emerged as a promising alternative to surgical lung biopsy for the diagnosis of interstitial lung disease. However, uncertainty remains regarding its overall complications due to a lack of procedural standardization including the size of cryoprobe utilized.METHODS:This is a prospective cohort study of a protocolized transbronchial cryobiopsy program utilizing a 2.4 mm cryoprobe. 201 consecutive subjects were enrolled at a single academic center.RESULTS:The average biopsy size was 106.2 ± 39.3 mm2. Complications included a total pneumothorax rate of 4.9% with 3.5% undergoing chest tube placement. Severe bleeding defined by the Nashville Working Group occurred in 0.5% of cases. There were no deaths at 30-days.DISCUSSION:A protocolized transbronchial cryobiopsy program utilizing a 2.4 mm cryoprobe in can achieve a high diagnostic yield with a favorable safety profile.

Purpose Tissue acquisition in lung cancer is vital for multiple reasons. Primary reasons reported for molecular testing failure in lung cancer biopsy specimens include insufficient amount of tumor cells provided and inadequate tissue quality. Robotic bronchoscopy is a new tool enabling peripheral pulmonary lesion sampling; however, diagnostic yield remains imperfect possibly due to the location of nodules adjacent to or outside of the airway. The 1.1-mm cryoprobe is a novel diagnostic tool and accesses tissue in a 360-degree manner, thus potentially sampling eccentric/adjacent lesions. This study examines the diagnostic yield of the cryoprobe compared to standard needle aspiration and forceps biopsy. It additionally evaluates yield for molecular markers in cases of lung cancer. Methods This is a retrospective analysis of 112 patients with 120 peripheral pulmonary lesions biopsied via robotic bronchoscopy using needle aspirate, forceps, and cryobiopsy. Results The overall diagnostic yield was 90%. Nearly 18% of diagnoses were made exclusively from the cryobiopsy sample. Molecular analysis was adequate on all cryobiopsy samples sent. Digital imaging software confirmed an increase in quantity and quality of samples taken via cryobiopsy compared to needle aspirate and traditional forceps biopsy. Conclusion Using the 1.1-mm cryoprobe to biopsy PPN combined with the Ion robotic bronchoscopy system is safe, feasible, and provides more diagnostic tissue than needle aspirates or traditional forceps biopsies. The combination of cryobiopsy with robotic-assisted bronchoscopy increased diagnostic yield, likely due to its 360-degree tissue acquisition which is beneficial when targeting extraluminal lesions adjacent to the airway.

The American Thoracic Society Core Curriculum updates clinicians annually in adult and pediatric pulmonary disease, medical critical care, and sleep medicine at the annual international conference. The 2021 Pulmonary Core Curriculum focuses on lung cancer and include risks and prevention, screening, nodules, therapeutics and associated pulmonary toxicities, and malignant pleural effusions. Although tobacco smoking remains the primary risk factor for developing lung cancer, exposure to other environmental and occupational substances, including asbestos, radon, and burned biomass, contribute to the global burden of disease. Randomized studies have demonstrated that routine screening of high-risk smokers with low-dose chest computed tomography results in detection at an earlier stage and reduction in lung cancer mortality. On the basis of these trials and other lung cancer risk tools, screening recommendations have been developed. When evaluating lung nodules, clinical and radiographic features are used to estimate the probability of cancer. Management guidelines take into account the nodule size and cancer risk estimates to provide recommendations at evaluation. Newer lung cancer therapies, including immune checkpoint inhibitors and molecular therapies, cause pulmonary toxicity more frequently than conventional chemotherapy. Treatment-related toxicity should be suspected in patients receiving these medications who present with respiratory symptoms. Evaluation is aimed at excluding other etiologies, and treatment is based on the severity of symptoms. Malignant pleural effusions can be debilitating. The diagnosis is made by using simple pleural drainage and/or pleural biopsies. Management depends on the clinical scenario and the patient's preferences and includes the use of serial thoracentesis, a tunneled pleural catheter, or pleurodesis.

Background: The coronavirus disease 2019 (COVID-19) pandemic has drastically affected hospital and operating room (OR) workflow around the world as well as trainee education. Many institutions have instituted mandatory preoperative SARS-CoV-2 PCR nasopharyngeal swab (NS) testing in patients who are low risk for COVID-19 prior to elective cases. This method, however, is challenging as the sensitivity, specificity, and overall reliability of testing remains unclear. Objectives: The objective of this study was to assess the concordance of a negative NS in low risk preoperative patients with lower airway bronchoalveolar lavage (BAL) specimens obtained from the same patients. Methods: We prospectively sent intraoperative lower airway BAL samples collected within 48 h of a negative mandatory preoperative NS for SARS-CoV-2 PCR testing. All adult patients undergoing a scheduled bronchoscopic procedure for any reason were enrolled, including elective and nonelective cases. Results: One-hundred eighty-nine patients were included. All BAL specimens were negative for SARS-CoV-2 indicative of 100% concordance between testing modalities. Conclusions: These results are promising and suggest that preoperative nasopharyngeal SARS-CoV-2 testing provides adequate screening to rule out active COVID-19 infection prior to OR cases in a population characterized as low risk by negative symptom screening. This information can be used for both pre-procedural screening and when reintroducing trainees into the workforce.

Background: Argon plasma coagulation (APC) is a tool used in the management of tracheobronchial obstruction or bleeding. Complications include gas embolism which can cause devastating effects including hemodynamic instability, cardiac arrest, and stroke. Multiple theories as to how gas embolism occurs with APC have been postulated; however, none have identified the exact mechanism. Objectives: To identify the mechanism by which APC causes gas embolism in the tracheobronchial tree. Methods: Using an explanted porcine tracheobronchial tree with lung parenchyma, the APC catheter was applied through noncontact and direct contact to the endobronchial airway mucosa via flexible bronchoscopy. This was done at multiple gas flow settings and pulse durations. Visual changes in the mucosa were photographed, videoed, and described. Results: Gross evidence of submucosal gas transfer occurred when the APC catheter was in direct contact with the mucosa at all gas flow settings in all applications, despite using shorter pulse durations. Whenever the catheter was not in contact with the mucosa, there was no transfer of gas at any gas flow setting or pulse duration. Conclusions: Direct mucosal contact with the APC probe leads to submucosal gas deposition and is a likely mechanism for gas entry into the intravascular space. In reported cases of APC-associated gas embolism, presence of a vascularized endobronchial tumor may have increased the risk of gas tracking into the intravascular space. Care should be taken when applying APC during brisk bleeding or limited vision, as inadvertent mucosal contact may occur and could increase the risk of gas embolism.

To the Editor: Chronic thromboembolic pulmonary hypertension (CTEPH), an infrequent although serious complication of acute pulmonary embolism (PE), results from the fibrotic transformation of pulmonary artery (PA) thrombi leading to chronic obstruction of PAs and associated remodeling of the microvasculature.1 CTEPH is the only cause of severe pulmonary hypertension that is potentially curable via surgery. Pulmonary endarterectomy is the treatment of choice for CTEPH in patients with the surgically accessible disease and often results in significant improvements in right ventricular function.2 Bronchoscopy with convex probe endobronchial ultrasound (EBUS) is an established tool for examining mediastinal and hilar lymph nodes. EBUS provides unique access to the central pulmonary and proximal lobar arteries. Several case reports have described the identification of acute PE during the EBUS examination.3–6 To our knowledge, EBUS has not been used to characterize the appearance of chronic thromboemboli in the PA vasculature. We report the first use of vascular endobronchial ultrasound (VEBUS) to detect many of the characteristic angiographic signs of CTEPH. We report a 64-year-old male, a former smoker with a past medical history of the chronic obstructive pulmonary disease who initially presented with several months of worsening shortness of breath on exertion. Computed tomography angiogram (CTA) showed a large thrombus in the right main PA as well as eccentric thrombus with recanalization and webs in the bilateral lobar and segmental arteries consistent with chronic PE. Echocardiogram showed a severely dilated right ventricle with moderate right ventricular hypertrophy, moderate to severe tricuspid regurgitation, and a right ventricular systolic pressure of 100 mm Hg consistent with severe pulmonary hypertension. A ventilation-perfusion scan revealed bilateral mismatched perfusion defects compatible with CTEPH. He was treated with oral anticoagulation with no improvement of his symptoms. The decision was made to undergo pulmonary endarterectomy. After the patient was intubated and before the start of the surgery, EBUS was performed to examine the central and proximal lobar PAs as previously described.7 The examination was initiated by advancing the EBUS bronchoscope into the right lower lobe to visualize the right lower lobe PA (basal trunk) located between 12 and 3 o'clock position. Once the right lower lobe PA is visualized between the 12 and 3 o'clock position, the scope is slowly fanned clockwise and counterclockwise to visualize the entire vessel at this level. The scope was retracted and turned counterclockwise to following the course of the interlobar PA on the medial wall of the right bronchial tree until the level of the carina, where the right main PA and the PA trunk were seen. During this process, the scope was fanned clockwise and counterclockwise every 1 cm to see the entire vessel. The scope was then advanced distally to the left lower lobe bronchus between 9 and 12 o'clock position to examine the basal trunk. The scope was then slowly retracted into the left main bronchus while scanning between the 9 and 12 o'clock positions to examine the interlobar artery and rotated towards 9 o'clock to examine the left upper lobar artery branches. Finally, the main PA was visualized by placing the scope at the 12 o'clock position in the proximal left mainstem bronchus. Again, the scope was fanned clockwise and counterclockwise every 1 cm during scope withdrawal to see the entire vessel. The EBUS balloon was utilized as needed during the procedure to obtain good visualization of the vasculature. Doppler mode was used to assess blood flow when areas of narrowing or obstruction were noted. A frequency of 12 MHz was used for the procedure. Using convex probe EBUS, we were able to identify several findings consistent with the diagnosis of chronic thromboembolic pulmonary disease including thickening of the right interlobar PA wall (Fig. 1), an intraluminal thrombus (Fig. 2), and an intraluminal fibrous PA web (with corresponding CTA image) (Fig. 3). The patient underwent pulmonary endarterectomy with good outcomes after surgery and the resolution of his pulmonary hypertension.FIGURE 1: Arrow pointing at hyperechoic horizontal line parallel to the right interlobar pulmonary artery vessel wall consistent with thrombus lining the wall (A) and a comparison image with arrow pointing at a normal right interlobar pulmonary artery vessel wall (B).FIGURE 2: Wavy hyperechoic density adjacent to the right interlobar pulmonary artery wall consistent with organized thrombus (arrow).FIGURE 3: A, Endobronchial ultrasound image with Doppler mode revealing an intraluminal fibrotic web (larger arrow) and intravascular thrombus (smaller arrow) in the right intralobar pulmonary artery, both observed as a heterogenous hypoechoic filling defect within the vessel. B, Computed tomography angiography of the chest, coronal view, and the arrow pointing at the right intralobar pulmonary artery intravascular fibrotic web.Ventilation-perfusion scan, CTA, and pulmonary angiography are the primary imaging techniques currently used to diagnose chronic thromboembolic disease and identify patients who may benefit from pulmonary endarterectomy.2 The angiographic patterns associated with the presence of organized thromboembolic material are mainly intimal irregularity, pouch defects, bands, and webs traversing the vascular lumen, and abrupt vascular cutoff denoting complete occlusion of vessels.8 One retrospective study looked at patients with a known diagnosis of acute PE on CTA. In 32 patients with central PE, EBUS was found to have a 97% accuracy in detecting PE compared with CTA.7 EBUS, a well-established modality for the assessment of hilar and mediastinal lymph nodes, could potentially be an important minimally invasive tool to visualize the location and characteristics of chronic thromboembolic disease within the PAs. Determining the proximal extent of disease in the PA is a critical part of patient selection, as the distal disease may not be amenable to surgery.8 Using VEBUS we were able to identify several angiographic signs characteristic of CTEPH, including: (a) thrombus lining the vessel wall, (b) organized intravascular thrombus, and (c) intravascular fibrotic web. VEBUS is a minimally invasive tool that carries minimal procedural risk and no risk of radiation exposure, or risks associated with the administration of intravenous contrast. Further experience will determine if VEBUS can add to the currently available imaging techniques in the diagnosis and management of CTEPH. We believe EBUS may have a role in the evaluation of some patients with CTEPH, to help determine the proximal extent of disease. We have had cases in whom CTA and even pulmonary angiography has been misleading and, at time of surgery, the more proximal organized disease is found, allowing a dissection plane to be developed and extended distally. In addition, VEBUS could add real-time intraprocedural visualization for endovascular interventions. VEBUS has its limitations, as the size of the EBUS probe (6.9 mm) prevents the evaluation of the PA vasculature much beyond the branch point of the lobar PAs. Thus, with the current technology, chronic thromboemboli in the lobar and more distal PA branches cannot be adequately assessed. Also, EBUS assessment of the central PA vasculature could miss some of the endovascular diseases. Further studies comparing findings on EBUS imaging and CTA are needed. We conclude that VEBUS is a minimally invasive tool that can visualize the location and characteristics of chronic thromboembolic disease within the central PAs. VEBUS can detect angiographic signs characteristic of CTEPH, including vascular wall thickening due to lining thrombus, organized intravascular thrombus, and fibrotic intravascular bands. VEBUS could potentially be used as a preoperative assessment tool in patients undergoing pulmonary endarterectomy. Christian Ghattas, MD* Richard N. Channick, MD† Cameron D. Wright, MD‡ Gus J. Vlahakes, MD§ Colleen Channick, MD†*Division of Pulmonary, Critical Care, and Sleep Medicine, The Ohio State University Wexner Medical Center, Columbus, OH†Division of Pulmonary, Critical Care, Sleep Medicine, Clinical Immunology and Allergy David Geffen School of Medicine at UCLA Los Angeles, CA‡Divisions of ‡Thoracic Surgery§Cardiac Surgery, Massachusetts General Hospital, Boston, MA

SESSION TITLE: Procedures Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: October 18-21, 2020 PURPOSE: Transbronchial lung cryobiopsy (TBLC) has recently emerged as a promising less invasive alternative to SLB for the diagnosis of interstitial lung diseases. There have been many recent studies showing high complication rates and low diagnostic yield of cryobiopsy. These results have led to some debate in terms of the safety, efficacy and utility of TBLC. Herein we describe our experience with TBLC with regards to safety utilizing a standardized protocol. METHODS: This is a retrospective case series of TBLC performed between 2017-2020. TBLC were performed under general anesthesia with rigid bronchoscopy. The airway was transitioned to an ETT if the patient was unable to tolerate rigid bronchoscopy. An endobronchial blocker, radial EBUS and fluoroscopy were utilized for every case. A 2.4 cryoprobe was utilized to obtain biopsies. Patients were followed for minimum of 6 months for diagnostic accuracy. RESULTS: 143 patients were identified over a 3-year period. Demographics are shown in table 1. 95% of patients were non-smokers or ex-smokers. 89.5% were performed with rigid bronchoscopy. Average DLCO was 58.2 ± 20.4%. Complications are listed in Table 2. The rate of pneumothorax was 5.5% with 5/8 requiring a chest tube. There were no cases of prolonged air leak. Of note the average DLCO in patient with pneumothorax was 25% compared to 59% (p < 0.001). There was 1 case of severe hemoptysis which required overnight hospitalization. There was 1 high risk case where anticipated outcome was for ICU admission overnight. Overall 30-day mortality was 0. The patient was successfully liberated from the ventilator POD1 and discharged. The average biopsy size was 1.02 ± 0.2 cm. 40% had one lobe sampled, 59% of patients had two lobes sampled, and 1% had 3 lobes sampled. Organizing pneumonia was the most common diagnosis (21%), followed by UIP/IPF (18%), sarcoidosis (14%), hypersensitivity pneumonitis (13%), CTD-ILD (9%), drug induced pneumonitis (9%), and others (16%). The most common lobes sampled was the RLL followed by the RUL. A diagnosis was achieved in 96%. CONCLUSIONS: Our experience suggests that TBLC can be performed safely with an acceptable diagnostic yield of > 90% when performed with a standardized protocol by experienced interventional pulmonologists on an outpatient basis. Our protocol includes the use of general anesthesia, rigid bronchoscopy transitioning to an ETT when needed, an endobronchial blocker, radial EBUS, a 2.4 cryoprobe and fluoroscopy. Our pneumothorax rate was 5.5% with 3.5% requiring a chest tube and no prolonged air leaks. Of note a lower DLCO was strongly associated with risk for pneumothorax. There was 1 case of severe hemoptysis. In conclusion, our data suggests TBLC remains a promising and safe alternative to SLB. CLINICAL IMPLICATIONS: We show that transbronchial cryobiopsy can be performed safely, and provide a high diagnostic yield for the diagnosis of ILD. DISCLOSURES: no disclosure on file for Mathew Carroll; My spouse/partner as a Consultant relationship with Actelion Please note: $20001 - $100000 Added 04/20/2020 by Colleen Channick, source=Web Response, value=Consulting fee My spouse/partner as a Consultant relationship with Bayer Please note: $5001 - $20000 Added 04/20/2020 by Colleen Channick, source=Web Response, value=Consulting fee No relevant relationships by Tao He, source=Web Response No relevant relationships by Catherine Oberg, source=Web Response No relevant relationships by Scott Oh, source=Web Response No relevant relationships by Reza Ronaghi, source=Web Response No relevant relationships by Irawan Susanto, source=Web Response

SESSION TITLE: Medical Student/Resident Diffuse Lung Disease SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Idiopathic diffuse pulmonary ossification is an extremely rare disease that often presents incidentally on chest imaging. While the initial course can often be indolent, the disease course can be severe, and in some cases, fatal. Here, we describe a case of a 21-year-old female who was incidentally diagnosed with diffuse pulmonary ossification. CASE PRESENTATION: The patient underwent tuberculin skin test for school clearance and was noted to have induration to 16 mm with subsequent negative QuantiFERON gold testing. Chest radiograph showed diffuse bilateral peribronchial thickening and nodular interstitial abnormality. The patient reported mild progressive dyspnea on exertion and intermittent dry cough. Her vital signs were unremarkable including an oxygen saturation of 97% on room air. On exam, her lungs were clear to auscultation. Initial computed tomography (CT) scan of the chest showed extensive bilateral centrilobular and peribronchvascular nodules with varying levels of calcification (image 1). Repeat CT scan at 3 months showed no change. Laboratory investigations including calcium, phosphate, sputum acid-fast bacilli, fungal serologies, and rheumatologic screen were normal. Spirometry showed an isolated mild reduction in the DLCO. Bronchoscopy with transbronchial cryobiopsy of the RLL showed pulmonary parenchyma with focal ossification without granulomas, malignancy or amyloid. Cultures were negative. DISCUSSION: Diffuse pulmonary ossification involves the formation of mature bone in the lung and occurs in two forms: nodular and dendriform, both of which can have idiopathic and secondary forms [1, 2]. Ossification typically presents in older men, though has been reported in women or younger adults. Commonly, patients present with absent to minimal symptoms of dyspnea and radiographic findings are out of proportion to symptoms. Spirometry testing is often initially normal but can develop a restrictive pattern with decreased DCLO in later stages. Chest imaging findings include bilateral diffuse calcified micronodules or dense ground glass opacities, with predilection for the lower lobes. Pathology typically reveals ossification and calcification within the alveoli. In later stages, alveolar septal thickening and interstitial fibrosis may develop. Diagnosis can often be made on imaging findings alone, though it can be confirmed with bronchoscopic or surgical biopsy if diagnosis is uncertain. Therapies target lowering serum calcium levels, though no treatments have been shown to affect the progression of disease. For patients with a more aggressive course, lung transplant may be considered [3]. CONCLUSIONS: Pulmonary ossification is a rare, often asymptomatic disorder, that should be suspected in patients with characteristic imaging findings. Early identification can help to monitor progression, though no clear disease modifying therapies have been identified. Reference #1: 1.Tseung J, Duflou J. Diffuse pulmonary ossification: an uncommon incidental autopsy finding. Pathology 38: 45-48, 2006. Reference #2: 2. Reddy TL, von der Thüsen J, Walsh SL. Idiopathic dendriform pulmonary ossification. J Thorac Imaging 27: W108-W110, 2012. Reference #3: 3. Matsuo H. et al, Progressive Restrictive Ventilatory Impairment in Idiopathic Diffuse Pulmonary Ossification Intern Med. 2018 Jun 1; 57(11): 1631–1636 DISCLOSURES: No relevant relationships by Jessica Channick, source=Web Response My spouse/partner as a Consultant relationship with Actelion Please note: $20001 - $100000 Added 04/20/2020 by Colleen Channick, source=Web Response, value=Consulting fee My spouse/partner as a Consultant relationship with Bayer Please note: $5001 - $20000 Added 04/20/2020 by Colleen Channick, source=Web Response, value=Consulting fee No relevant relationships by Tamas Dolinay, source=Web Response