Fig. 9.1
(a, b) Computed tomographic (CT) appearance of thoracic periaortitis. The perivascular tissue surrounds (a) the upper portion of descending aorta (arrow), and (b) the ascending thoracic aorta (arrow). (c, d) Magnetic resonance (MR) angiography of thoracic periaortitis with epiaortic artery involvement. The scans show diffuse caliber reduction of the right subclavian artery (arrows) (c) and significant caliber reduction of left subclavian artery (arrows) (d).(e–g) 18F-Fluorodeoxyglucose (FDG) positron emission tomography (PET)-CT evidence of active chronic periaortitis. The scans (e), coronal view, (f), sagittal view, and (g) axial view show increased uptake of FDG at the thoracic aorta and upper abdominal aorta levels (arrows)
In a recent study, we retrospectively investigated the thoracic aorta and epiaortic artery involvement in a large cohort of CP patients [2]. CP patients were eligible for this study if they had appropriate imaging studies examining the inflammatory involvement of the thoracic (and abdominal) large vessels, which included contrast-enhanced chest CT or MRI and whole-body FDG-PET. We found thoracic vessel involvement in approximately one third of the cases (28 of the 77 eligible patients, 35 %). More specifically, three main patterns were observed: thoracic periaortitis, periaortitis with thoracic aorta aneurysm, and thoracic aorta aneurysm without periaortitis. In 15 of the 28 CP patients (54 %) with thoracic periaortitis, the perivascular tissue surrounded a thoracic aorta of normal caliber; tissue enhancement was variable on CT or MRI, probably reflecting disease activity. The median FDG uptake grade at PET studies was similar at the abdominal aorta and thoracic aorta levels. Seven of these 15 patients also showed epiaortic artery involvement, commonly of the origin of the carotid arteries. Periaortitis surrounding a thoracic aortic aneurysm was observed in six patients (21 %), two of them with epiaortic artery involvement. The remaining seven cases (25 %) had a thoracic aortic aneurysm without periaortitis; this pattern was included as a disease-related manifestation because it is a potential complication of large-vessel vasculitides where it is thought to be due to chronic inflammation of the aortic wall.
This study has also offered the possibility to analyze thoracic vascular/perivascular biopsies of three patients (two after carotid endarterectomy and one after surgical repair of thoracic aortic aneurysm) that showed a histologic pattern strikingly similar to that found in abdominal CP [6]. Vascular inflammation predominated in the adventitia and consisted of lymphocytes, histiocytes, plasma cells, and eosinophils; this adventitial infiltrate was often organized in follicular aggregates, sometimes with germinal centres rich in lymphocytes, which clustered around adventitial vasa vasorum. The aggregates are considered examples of ectopic lymphoneogenesis that is an expression of a highly structured immune-mediated response, as observed in many autoimmune diseases. These histological findings, together with the imaging features, suggest that CP may arise as a primary large-artery inflammatory disease that in some cases may involve not only the abdominal aorta but also other large vessels. In these cases we should always keep in mind that same patterns of thoracic CP may be seen in other large vascular disease, especially GCA and TA that generally lack the thick periaortic cuff seen in CP but, as discussed below, differential diagnosis sometimes is challenging.
9.3 Complications of Thoracic Periaortitis
Complications of thoracic involvement in CP have never been illustrated in literature. The only well illustrated data concern the inflammatory thoracic aorta aneurysms that, less frequently than the atherosclerotic ones, tend to produce acute dissection needing prompt surgical repair [17, 18]. This aspect was also confirmed in our group of patients: only 4 of the 13 thoracic aortic aneurysms (either with or without periaortitis) underwent surgical or endovascular repair [2]. By reviewing our published cohort of patients with diffuse periaortitis, we interestingly disclosed that thoracic disease was asymptomatic in about 85 % of the cases and, in the few symptomatic ones, the clinical pattern was related to epiaortic artery involvement: two patients had hoarseness secondary to recurrent laryngeal nerve paralysis, two patients had unilateral deficit in arm strength and asymmetrical pulses/blood pressure values, three patients had upper limb claudication, upper limb paresthesias, and dry cough.
9.4 Chronic Periaortitis with Thoracic Aorta Involvement: A Distinct Subset?
Until 2015, the anecdotal published cases of diffuse CP had not provided any detailed information about the clinical aspects of this new disease pattern. Our recent study also explored demographic, laboratory, and clinical features in patients with and without thoracic disease (28 and 49 patients respectively) [2]. Patients with thoracic disease had a significantly higher female prevalence, a greater age at disease onset, and a higher prevalence of disease-related symptoms, namely systemic symptoms (e.g., fatigue, anorexia, weight loss) and back or abdominal pain. Patients with thoracic disease also tended to have higher levels of inflammatory markers (erythrocyte sedimentation rate and C-reactive protein) than patients without thoracic disease, although the differences were not statistically significant. No differences in the two groups were found in terms of prevalence of autoantibodies, associated autoimmune diseases, atherosclerotic risk factors, and established atherosclerotic diseases.
By keeping in mind the recent hypothesis that CP, especially when there is thoracic involvement (as an expression of systemic disease), should be included in the spectrum of IgG4-related disease (IgG4-RD) we analyzed, where available (45 of the 77 cases), the levels of serum IgG4 in patients with and without thoracic disease [7, 19]. Only about 20 % of patients in both groups exhibited high serum IgG4 levels with no difference between the two groups. Nevertheless, immunohistochemistry on thoracic CP biopsies revealed in two of the three cases a significant IgG4+/CD138+ plasma cell ratio (>40 %) suggesting that in such cases CP may be considered IgG4-related. These patients, however, showed no other organ lesions typical of IgG4-RD.
The female prevalence as well as the advanced age at disease onset in patients with thoracic aorta involvement is a feature similar to other large-vessel vasculitides, particularly GCA. These clinical aspects, in addition to the histopathologic finding of active adventitial inflammation lend further support to the hypothesis that in a subset of patients CP may be considered a primary large-vessel inflammatory disease.
9.5 Differential Diagnosis with Other Large-Vessel Diseases
When managing CP patients with thoracic aorta involvement, it is mandatory to exclude other diseases that diffusely affect the aorta and its branches. First, diffuse CP normally refers to idiopathic clinical entities and does not include cases secondary to different etiologies such as use of drugs, cancer (primary or metastatic disease), carcinoid syndrome, radiotherapy, trauma, major abdominal surgery, and infections. These conditions, illustrated in detail in Chap. 15, always need to be considered when approaching a CP patient [20].
There are numerous inflammatory/autoimmune conditions that diffusely affect the aorta and its major branches (Table 9.1). These are defined as “aortitis” and typically lack the periaortic fibroinflammatory reaction that hallmarks CP. The distinction between aortitis and periaortitis is important for clinical and therapeutic implications. Aortitis is a pathological term that refers to the presence of areas of wall thickening and inflammation; it is generally mainly lymphoplasmacytic or lymphohistiocytic, with giant cells and well-formed granulomas in the context of the medial layer. Atherosclerosis is often found in the intima, whereas, unlike in periaortitis, the adventitia rarely shows inflammation and fibrosis [3].
Table 9.1
Main differential characteristics of conditions that may cause diffuse large artery disease
Diffuse chronic periaortitis | Giant cell arteritis | Takayasu arteritis | Erdheim-Chester disease | Infectious aortitis | |
|---|---|---|---|---|---|
Demographic characteristics | |||||
Female-to-male ratio | 1:1 | 3:2 | 7:1 | 1:3 | 3:1 |
Age, median at the onset | >60 years | > 50 years | < 40 years | > 30 years | All age groups |
Clinical manifestations | |||||
Constitutional symptomsa | ++ | ++ | ++ | + | ++ |
Abdominal symptomsb | +++ | − | + | + | + |
Ureteral obstruction | ++ | − | − | ++ | − |
Upper limb symptomsc | ± | ++ | +++ | + | − |
Cranial symptomsd | − | +++ | − | + | − |
Autoimmunity | |||||
Associated immune-mediated diseases | Various | Polymyalgia rheumatica
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