How to distinguish pulmonary vasculitis from pulmonary thromboembolism Xiong Changming, Fu Wai Cardiovascular Hospital Pulmonary vasculitis is a general term for a group of diseases in which systemic necrotizing vasculitis involves the pulmonary vasculature. It is essentially a rheumatic immune disease. Pulmonary vasculitis often causes widespread stenosis or even occlusion of pulmonary vessels and leads to pulmonary hypertension, which is clinically manifested by chest tightness, shortness of breath and hemoptysis, etc. Chest X-ray shows limited sparse lung texture and radionuclide lung ventilation/perfusion imaging also shows lung segment defects, which is easily misdiagnosed as pulmonary embolism. However, pulmonary vasculitis often lacks the predisposing factors for deep vein thrombosis. Clinically, systemic symptoms such as fever, cough, sputum and malaise are often seen, and some patients may have renal damage, skin damage, arthralgias and peripheral nerve damage. In this paper, we analyze the causes of misdiagnosis and further improve the differential diagnosis of pulmonary embolism by combining clinical case reports. Xiong Changming, Department of Cardiovascular Medicine, Fu Wai Hospital, Beijing, China Case 1 is a 28-year-old female with intermittent chest pain and fever of 8 years. She was admitted to the hospital on October 11, 2005 with intermittent chest pain and fever for 8 months. The patient presented 8 months ago with no obvious cause of right chest and back and scapular region pain, aggravated by inspiration, without shortness of breath after activity. 2 weeks later, she developed chills, fever (up to 39℃, cough, coughing sputum, occasionally blood in the sputum. The local hospital suspected right upper pulmonary tuberculosis and gave regular anti-tuberculosis treatment. 2 months later, he still had intermittent fever, with body temperature fluctuating between 37.5 ℃ and 38 ℃. He had been treated with various antibiotics since then, but still did not work. In August, he was diagnosed with pulmonary embolism after pulmonary ventilation and perfusion examination and pulmonary vascular computed tomography (CT) examination at an outside hospital. Warfarin anticoagulation was administered, but hypothermia was still present. Since the onset of the disease, the patient was in a fair general condition, without weight loss, normal diet and sleep, and no significant symptoms in daily physical activities. On examination: no abnormal blood pressure in the extremities, and vascular murmur was heard in the right lung. Blood sedimentation was 70 mm/h, C-reactive protein was 23.3 mg/L, liver and kidney function were normal, and the complete set of immunological tests (autoantibodies, anti-adhesion point antibodies, anti-Sm antibodies, anti-SSA antibodies, anti-SSB antibodies, anti-RNP antibodies, anti-cardiolipin antibodies, etc.) were normal. Cardiac ultrasonography was not abnormal. No thrombosis was seen in the deep veins of both lower limbs. Pulmonary vascular CT: Widened pulmonary arteries, right and left pulmonary artery trunks, two lower pulmonary artery trunks, thickened walls and narrowed lumen of the pulmonary artery branches in the left lingual lobe, right middle lobe and each basal segment of the two lower lobes. The right middle lobe was not visualized. The wall of the thoracic aorta and the branch vessels of the cephalic brachial artery were not thickened, and the lumen was not narrowed, with good visualization, suggesting pulmonary vasculitis. Pulmonary angiography showed irregularities in the walls of the vessels of the middle and lower lobes of the right pulmonary artery, and the lumen was thin, narrowed, or even occluded, suggesting pulmonary vasculitis. After the patient was admitted to the hospital and treated with prednisone, the body temperature quickly returned to normal, and the blood sedimentation and C-reactive protein gradually decreased. Case 2 female, 26 years old, was admitted to the hospital with weakness and shortness of breath after activity for more than 1 year, aggravated with fever for 1 month. The patient felt right-sided chest pain with no obvious cause 1 year ago, and developed chest tightness and weakness after activity, which was relieved after rest. Since then, the symptoms gradually worsened, and cough and hemoptysis appeared. An out-of-hospital examination of pulmonary perfusion with nuclear lung ventilation suggested multiple pulmonary perfusion sparing or defect, and pulmonary embolism was diagnosed. In the past 1 month, his symptoms worsened and he developed intermittent fever and physical Author Affiliation: 100037, Beijing, China Academy of Medical Sciences Institute of Cardiovascular Diseases, China Union Medical College Fu Wai Cardiovascular Hospital Pulmonary Vascular Disease Diagnosis and Treatment Center Author Introduction: Changming Xiong, MD, PhD, Associate Chief Physician He is mainly engaged in clinical and basic research of cardiovascular disease, especially pulmonary vascular disease. The temperature was 37.5~38.5℃, and the out-of-hospital anti-infection treatment was ineffective. On admission: body temperature 37℃, blood pressure 120/70mmHg (1mmHg=0.133kPa), respiratory rate 15 breaths/min, heart rate 82 breaths/min, vascular murmur audible in both lung fields, hyperactive 2nd heart sound in the pulmonary valve auscultation area, grade II/6 systolic murmur audible in the tricuspid valve auscultation area, abdominal tenderness, liver not palpable under the ribs, no swelling in both lower limbs. Blood sedimentation was 65 mm/h. C-reactive protein was 67.3 mg/L. Liver and renal functions were normal. The complete set of immunological tests (autoantibodies, anti-adhesion site antibodies, anti-Sm antibodies, anti-SSA antibodies, anti-SSB antibodies, anti-RNP antibodies, anti-cardiolipin antibodies, etc.) were normal. pH was 7.44, PO2 was 77.1 mm Hg, and PCO2 was 35 mm Hg. Cardiac ultrasound. The right atrium and ventricle were enlarged, the left ventricular end-diastolic internal diameter was 46 mm, the left ventricular ejection fraction was 0.56, and the right ventricular internal diameter was 27 mm. The systolic pulmonary artery pressure was estimated at 74 mm Hg. No thrombosis was observed in the deep veins of both lower extremities. Nuclear pulmonary perfusion examination suggested multiple sparse or defective perfusion in both lungs. Pulmonary vascular enhancement CT: widening of the pulmonary arteries, with no clear visualization of the post-apical segment of the left upper lobe and each basal segment of the right lower lobe. The anterior and lingual segments of the left upper lobe of the lung were thinning, with uneven lumen thickness, and no filling defects were seen in the pulmonary vessels at all levels. The wall of the left subclavian artery and its distal descending aorta was thickened, and there was no narrowing or dilatation of the lumen, suggesting that the pulmonary artery was involved in aortitis. After admission, the patient was treated with prednisone and warfarin, and his symptoms were significantly relieved and his body temperature was normal. This is a typical case of 2 cases of pulmonary vasculitis misdiagnosed as pulmonary embolism, which is also one of the most common diseases misdiagnosed as pulmonary embolism at present. One of the reasons is that pulmonary vasculitis is relatively rare in clinical practice and clinicians are not aware of it. The second reason is that pulmonary embolism and pulmonary vasculitis have many similarities: (1) exertional shortness of breath and hemoptysis; (2) electrocardiogram shows increased right ventricular load. ③Echocardiogram shows enlarged right atrium and ventricle and pulmonary hypertension. ④Nuclear pulmonary ventilation perfusion suggests pulmonary perfusion deficit. However, if these two diseases are carefully analyzed, it is not difficult to find their differences: ①Pulmonary embolism mostly has susceptibility factors of venous thrombosis. ②Pulmonary vasculitis patients are mostly middle-aged and young, and are more common in women. ③Pulmonary vasculitis patients can hear vascular murmurs in the lung fields on examination. ④Pulmonary vasculitis is characterized by fever, cough, malaise and other systemic symptoms. (5) Some pulmonary vasculitis is a pulmonary manifestation of connective tissue disease, so patients may have other manifestations of connective tissue disease such as kidney damage, skin damage, joint swelling and pain, and peripheral nerve damage. (6) Pulmonary vasculitis may have abnormalities such as rapid blood sedimentation, increased C-reactive protein, and positive rheumatoid factor, whereas pulmonary embolism does not show an increase in these inflammatory indicators. (7) X-ray chest film of pulmonary vasculitis leading to pulmonary hypertension shows enlarged right atrium and ventricle and prominent pulmonary artery segment, but instead of corresponding widening of pulmonary artery, thinning appears. In order to reduce misdiagnosis, the first step should be to raise awareness of the diagnosis of pulmonary vasculitis, which can be identified in most patients by clinical manifestations and routine examination. Pulmonary vascular enhancement CT and pulmonary angiography will help to differentiate the two if necessary: ①Pulmonary embolism manifests as filling defect of pulmonary vessels and lack of branches. ②Pulmonary vasculitis shows multiple stenosis, distortion, luminal thinning and dilatation, wall thickening, and ratty luminal changes in the pulmonary vessels, and in some patients, filling defects due to secondary thrombosis of the pulmonary arteries are seen. Pulmonary vasculitis is a treatable disease, and hormonal and/or immunosuppressive therapy during the early active phase will stop the progression of the inflammatory lesions, reduce the narrowing and occlusion of the pulmonary vessels, and decrease the development of pulmonary hypertension. When the inflammatory lesions of pulmonary vasculitis are stabilized, pulmonary vascular interventions (balloon dilation or stenting) are feasible to release the limited stenosis of the pulmonary vascular trunk. Therefore, early diagnosis and treatment of pulmonary vasculitis will significantly affect the prognosis. Delayed treatment makes the pulmonary artery pressure gradually increase, and eventually the patient loses mobility and has a very poor prognosis.