ABSTRACT
Takayasu arteritis (TAK) is a vasculitis that causes inflammation in the arterial walls of large blood vessels. The complication rate of pulmonary artery lesion in TAK has been reported to be relatively high. Severe pulmonary artery stenosis can cause pulmonary infarction in rare cases. A 48-year-old woman had experienced cough and fever persistently for 3 months and visited a city hospital. Contrast-enhanced computed tomography (CT) and positron emission tomography (PET)-CT scans revealed TAK complicated with left pulmonary artery lesion. Contrast-enhanced CT couldn’t detect wall thickening in the left smaller bifurcated pulmonary artery branch, but PET-CT did reveal this inflammation. Several weeks after we initiated treatment with high-dose prednisolone, the patient’s symptoms and inflammatory findings disappeared. PET-CT may be useful for evaluating the inflammation of the pulmonary artery in TAK, and high-dose steroid monotherapy as induction therapy may be effective for TAK complicated with pulmonary artery lesions causing pulmonary infarction.
INTRODUCTION
Takayasu arteritis (TAK) is a type of vasculitis causing inflammation in the arterial walls, including the aorta, common carotid, brachiocephalic, subclavian, coronary and pulmonary arteries. The complication rate of pulmonary artery lesion in TAK has been reported to be relatively high, ranging from 14 to 100% in previous studies [1, 2]. However, in rare cases, severe pulmonary artery stenosis causes pulmonary infarction. Here we report a rare case of TAK with pulmonary artery lesion causing pulmonary infarction.
CASE REPORT
A 48-year-old woman with no medical history had experienced cough for 6 months before hospitalization. She suffered from fever persistently for 3 months before hospitalization. Chest computed tomography (CT) showed a nodular shadow and mild effusion in the left S9 region. Despite antibiotic treatment, the patient’s symptoms persisted. She had no hypoxia. Physical examination revealed no wheezing, crackles, abnormal heart sounds, or other abnormal findings. Laboratory investigations showed Hb 100 (115–165 g/L), WBC 15.6 (4–8 × 109/L), Platelets 55.8 (150–450 × 109/μL) and CRP 74.7 (0-3 mg/L). The prothrombin time was 80 (70–140%), activated partial thromboplastin time was 31 (27–31 s), Fibrinogen 6.7 (1.8–3.2 g/L) and D-dimer 0.85 (0–1 μg/mL). Rheumatoid factor, antinuclear antibody and antineutrophil cytoplasmic antibody were negative. HLA-B52 was detected. No pathogens were detected in the bacterial culture tests from blood and sputum samples. No abnormal echocardiography findings indicated pulmonary artery hypertension (PAH) or intracardiac thrombus. Lower extremity venous echocardiography also revealed no abnormal findings. Contrast-enhanced CT showed infiltration shadows without contrast effect in the left S9 region and stenosis of the left lower pulmonary artery with arterial wall thickening (Fig. 1A). In addition, thickening of the aortic arch, ascending aorta, left common carotid artery and left subclavian artery were shown on contrast-enhanced CT. Similarly, positron emission tomography (PET)-CT revealed accumulation of fluorodeoxyglucose (FDG) in the left subclavian artery, ascending aorta, left lower pulmonary artery and its smaller bifurcated pulmonary artery branch, whose wall thickening couldn’t be detected by contrast-enhanced CT (Fig. 1B). In this case, pulmonary infarction likely resulted from vascular inflammation in the peripheral pulmonary arteries. Skin, gastrointestinal and ocular symptoms suggestive of other large vessel vasculitis such as Behcet’s disease were negative, and we diagnosed TAK based on the CHCC 2012 definition.
Figure 1.
Contrast-enhanced CT at the time of admission (A), PET-CT at the time of admission (B), chest contrast CT at 6 months after immunosuppressive treatment (C), PET-CT at 1 year after immunosuppressive treatment (D). With therapeutic intervention, pulmonary artery lesions (red and white circles) are improving. The left smaller bifurcated pulmonary artery branch was difficult to evaluate in contrast-enhanced CT, but showed accumulation on PET-CT (red circles). White arrows indicate FDG accumulation in the aorta, and red arrows indicate areas of pulmonary infarction.
We initiated prednisolone 1 mg/kg, which immediately relieved the patient’s fever. We also started antiplatelet agents because they have been reported to significantly reduce acute ischemic events compared with anticoagulant therapy [3]. The CRP normalized 2 weeks after treatment. Contrast-enhanced CT at 1 month after treatment revealed improvement in the diameter of the left subclavian artery and wall thickening of the pulmonary artery and a tendency for a reduction in pulmonary infarction size. We added azathioprine at the time of steroid tapering. Even after discharge, the steroid dose was smoothly tapered without any change in the patient’s physical condition. The thickening of the left pulmonary artery wall disappeared by 6 months after treatment (Fig. 1C). At 1 year after treatment, prednisolone was reduced to 5 mg, and azathioprine was administered at 100 mg. PET-CT showed that the FDG accumulation disappeared in the left pulmonary artery and further improvement occurred in the pulmonary infarct lesion (Fig. 1D).
DISCUSSION
Pulmonary infarction has been reported to occur in approximately 3% of patients with TAK complicated with pulmonary artery lesions [4]. However, there is little clinical information regarding the therapeutic strategy, prognosis, or relapse rate under immunosuppressive therapy in TAK with pulmonary infarction. In several previous case reports, glucocorticoid treatment was effective for TAK complicated with pulmonary artery lesion, and we have previously reported the course of TAK during the first year of glucocorticoid treatment with azathioprine [5].
No diagnostic serological markers such as specific autoantibodies have been established yet for TAK. Thus, imaging tests such as contrast-enhanced CT and magnetic resonance imaging (MRI) are important diagnostic tools for TAK. In addition, PET-CT is an effective imaging test for TAK because it enables the evaluation of the extent of arteritis lesions in the whole body. A previous study reported the sensitivity and specificity of PET-CT for detecting TAK to be 92.6 and 91.7%, respectively [6]. An analysis of pulmonary artery lesions in 29 patients with TAK showed that PET-CT has better diagnostic ability for pulmonary artery lesions than CT angiography or MRI and is also useful for monitoring the activity of pulmonary artery lesions, the reflecting treatment response. Thus, we consider PET-CT to be the preferred modality for analysing pulmonary artery lesions in patients with TAK [7].
Pulmonary artery lesion in TAK tends to occur unilaterally (slightly dominant on the right side) [8]. In a previous report that included 21 patients with TAK, 12 patients had abnormal findings on pulmonary perfusion scintigraphy, of whom 8 patients had no respiratory symptoms [9]. That study suggested that many patients might have TAK complicated with potential pulmonary artery lesion, despite the absence of respiratory symptoms. An association between TAK and PAH has also been reported, although our case didn’t result in PAH. Amongst patients with TAK without pulmonary artery involvement, 7.6% were complicated with PAH, whereas 61.7% of patients with TAK with pulmonary artery involvement were complicated with PAH. In addition, amongst those with TAK complicated with pulmonary artery involvement, the risk of mortality was high in patients with PAH [10]. Therefore, it is important to evaluate the pulmonary artery lesions and the complication of PAH in patients with TAK and to initiate immunosuppressive treatment before the pulmonary artery undergoes irreversible changes and causes pulmonary hypertension.
In our case, pulmonary infarction developed as a result of severe pulmonary artery stenosis based on TAK at 6 months after onset, although PAH didn’t occur. PET-CT was useful for evaluating the extent of pulmonary artery lesion in TAK. High-dose steroid monotherapy was effective as an induction therapy, and the pulmonary infarction lesion improved at 1 year after treatment under steroid tapering without any relapse in arteritis. Although TAK may rarely cause pulmonary infarction, it should be considered a cause of pulmonary infarction due to its significant impact on patient prognosis.
ACKNOWLEDGEMENT
The authors would like to thank the patient. The authors also acknowledge Enago (www.enago.jp) for the English language review.
Contributor Information
Takehiro Hirayama, Department of Respiratory Medicine and Clinical Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
Takayoshi Morita, Department of Respiratory Medicine and Clinical Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
Kenji Funakoshi, Department of Respiratory Medicine and Clinical Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
Yuko Yoshimine, Department of Respiratory Medicine and Clinical Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
Saki Minoda, Department of Respiratory Medicine and Clinical Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
Teruaki Murakami, Department of Respiratory Medicine and Clinical Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
Yasutaka Okita, Department of Respiratory Medicine and Clinical Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
Masashi Narazaki, Department of Respiratory Medicine and Clinical Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan; Department of Advanced Clinical and Translational Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
Atsushi Kumanogoh, Department of Respiratory Medicine and Clinical Immunology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan; Laboratory of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan; Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Suita, Osaka, Japan; Center for Infectious Diseases for Education and Research (CiDER), Osaka University, Suita, Osaka, Japan.
CONFLICT OF INTEREST STATEMENT
None declared.
FUNDING
None.
ETHICAL APPROVAL
Not applicable.
CONSENT
The first author (Dr Hirayama) received consent from the patient.
GUARANTOR
Takayoshi Morita is nominated as the manuscript’s guarantor.
DATA AVAILAVILITY
The data that support the findings of this study are available from the corresponding author, Takayoshi Morita, upon reasonable request.
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