Title: Incidental Life-Threatening Diagnosis During Endobronchial Ultrasound Bronchoscopy
Abstract: A 56-year-old man with a past history of morbid obesity and C5-C7 anterior diskectomy was admitted with subacute progressive quadriparesis and urinary retention. Cervical spine magnetic resonance imaging revealed T2 enhancement from C4 through T3 with significant cervical stenosis. The patient underwent immediate cervical laminoplasty, but had residual weakness, raising concern for alternative etiology. Magnetic resonance imaging enhancement was again seen on follow-up imaging. He was then started on dexamethasone for postoperative edema. Infectious workup including cerebrospinal fluid analysis was unrevealing. Given the differential included a paraneoplastic process, a computed tomography-positron emission tomography scan was obtained, which demonstrated fluorodeoxyglucose avid mediastinal and hilar lymph nodes. A pulmonary consult was obtained for endobronchial ultrasound (EBUS) bronchoscopy with transbronchoscopic fine needle aspiration (TBNA) biopsy of the enlarged mediastinal and hilar lymph nodes. He had mild hypercalcemia of 12.0 mg/dL. On hospital day 2, he underwent bronchoscopy with EBUS-TBNA of subcarinal lymph node (station 7), right hilar lymph node (station 11R), and left lower paratracheal lymph node (station 4L). During the procedure the EBUS bronchoscope was placed in the right main stem bronchus with identification of a bilobulated echogenic mass within the right pulmonary artery (Video 1, Supplemental Digital Content 1, https://links.lww.com/LBR/A134). Similar endoluminal mass causing flow limitation was also seen in the left main pulmonary artery. DISCUSSION Convex probe EBUS extends the view (ultrasound) of the flexible bronchoscope beyond the airway using a 7.5 MHz convex array ultrasound transducer mounted at the distal tip, with a penetration of 50 mm. The angle of ultrasound view is 90 degrees and the direction of digital view is 30 degrees forward oblique to the shaft of the bronchoscope. Right pulmonary artery is an ultrasound landmark, identified anteriorly in the proximal right main stem bronchus. Blood is anechoic (appears black) when free flowing, so under normal conditions the pulmonary arteries should be anechoic as well. The station 7 lymph node is identified with counterclockwise rotation of the ultrasound probe from the position of viewing the right pulmonary artery. The station 11R lymph node is identified with clockwise rotation of the ultrasound probe in reference to the right pulmonary artery. The station 4L lymph node is located just cranial to the left main pulmonary artery. The upper boarder of left main pulmonary is the separation between station 4L and 10L lymph nodes. In this case we incidentally saw large hyperechoic filling defects in both the main pulmonary arteries (Figs. 1A, B). Subsequent CT pulmonary angiogram confirmed the presence of pulmonary embolism (Fig. A).FIGURE 1: A and B, Endobronchial ultrasound image demonstrating a large hyperechoic filling defect in the right pulmonary artery with doppler demonstrating absence of flow within the defect.FIGURE A: Computed tomography pulmonary angiography demonstrating a central pulmonary embolism extending into the right and left pulmonary arteries and proximal branches.There are 5 reported cases of incidentally discovered central pulmonary embolism by EBUS in the literature. Four cases were confirmed by computed tomography angiogram (CTA) and 1 case by magnetic resonance pulmonary angiogram. All were treated with therapeutic anticoagulation.1–5 All pulmonary emboli incidentally found during EBUS were in patients undergoing a diagnostic or staging workup for a lung mass which underscores the high risk of venous thromboembolism (VTE) in this patient population frequently seen in the bronchoscopy suite. The incidence of pulmonary embolism seen by EBUS may be much higher given a prevalence of 3.1% of incidentally discovered pulmonary embolism by CT in patients with malignancy.6 In addition only right and left main pulmonary arteries with proximal branches are visualized in routine EBUS procedure, thus missing peripheral pulmonary embolism. A prospective trial of 32 patients with known proximal pulmonary emboli evaluated the operating characteristics and safety of confirming central pulmonary embolism with EBUS. Each patient underwent flexible bronchoscopy with EBUS within 24 hours of their initial diagnosis.6 Pulmonologists followed a systematic approach in visualizing the proximal lobar, main pulmonary arteries, and pulmonary arterial trunk with the EBUS probe. Using this technique they successfully visualized 97 of 101 pulmonary emboli as documented by CTA, and were able to detect at least 1 proximal pulmonary embolism in all 32 patients, demonstrating 100% sensitivity in a confirmatory role, and 96% accuracy in identifying proximal pulmonary emboli.7 All procedures were performed under moderate sedation, and procedure time was as low as 3 minutes by the end of the trial, without any complications experienced by the patients. Emboli missed by EBUS visualization were in lobar branches of the pulmonary arteries; however, given that all also had proximal pulmonary embolism visualized, treatment would not have been affected. The pulmonologists performing EBUS in this study had performed 120 procedures or less, suggesting that extensive experience is not needed for successfully diagnosing pulmonary embolism by EBUS.7 The characteristics of EBUS for primary diagnosis of pulmonary embolism have not been further examined; however, the demonstrated ability of EBUS to reliably visualize the proximal pulmonary arteries and proximal branches makes EBUS a fruitful diagnostic tool. CTA pulmonary angiogram remains the gold standard for diagnosis of VTE. However, risk of contrast-induced nephropathy, iodine allergy, radiation exposure in pregnant women, and hemodynamic instability precluding transport make many patients unsuitable for study by CTA. In total, 24% of patients in the PIOPED II study were, in fact, excluded for the above reasons.8 EBUS may offer an alternative, rapid, and well-tolerated mode of diagnosis to rule in a proximal pulmonary artery thrombus. The patient underwent a CTA of the chest that confirmed a saddle pulmonary embolism and was started on therapeutic heparin. Pathology of lymph node FNA biopsy ultimately showed non-necrotizing sterile granulomatous inflammation consistent with sarcoidosis. The patient tolerated the procedure well and was ultimately treated for hypercalcemia and a clinical diagnosis of neurosarcoid. REVERBERATIONS EBUS offers clear views of the main pulmonary arteries, and filling defects should be noted as true findings representative of VTE or tumor embolism until proven otherwise. EBUS has excellent operating characteristics in the confirmatory diagnosis of proximal pulmonary embolism. There may be a diagnostic role for EBUS in the diagnosis of pulmonary embolism in patients who are unable to tolerate CTA pulmonary angiography.
Publication Year: 2016
Publication Date: 2016-09-10
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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