Eosinophilic lung diseases - what the radiologist needs to know

Transcription

1 Eosinophilic lung diseases - what the radiologist needs to know Poster No.: C-0803 Congress: ECR 2014 Type: Authors: Keywords: DOI: Educational Exhibit E.-M. Heursen, R. Reina Cubero, F. Japon Sola; Cádiz/ES Pathology, Laboratory tests, Diagnostic procedure, CT-High Resolution, Conventional radiography, Thorax /ecr2014/C-0803 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 16

2 Learning objectives To know the most important imaging findings on conventional chest radiography and High Resolution CT (HRCT) in eosinophilic lung diseases, their radiologic-pathologic correlation and the additional analytic findings. Background The term "eosinophilic lung diseases" (ELD) summarizes a collection of pulmonary pathologies caused by an excess of eosinophilic granulocytes within the pulmonary parenchyma. ELD can be diagnosed if one of the following findings is present: A) Thoracic opacifications associated with peripheral eosinophilia B) Tissue eosinophilia within a lung biopsy C) Important eosinophilia within a bronchoalveolar lavage (BAL) They are classified into pathologies of known cause (parasitic infection, allergic bronchopulmonary aspergillosis, or drug toxicity), unknown cause (Loeffler's syndrome, acute and chroniceosinophilic pneumonia or idiopathic hypereosinophilic syndrome) and eosinophilic vasculitis (Churg-Strauss syndrome) (see figure 1). Images for this section: Page 2 of 16

3 Fig. 1: Table with overview of the different types of eosinophilic lung diseases of known and unknown origin Page 3 of 16

4 Findings and procedure details Some type of ELD have characteristic radiologic findings. However, others either don't have specific radiologic characteristics or share similar morphologies which makes them hard to distinguish. Therefore, it is critical to know the associated analytic and pathologic findings to give a correct diagnosis. For example, in patients with chronic asthma there are three different types of ELD: Bronchopulmonary aspergillosis, allergic vasculitis and chronic eosinophilic pneumonia. The allergic Bronchopulmonary aspergillosis(abpa) is one of the ELD of known cause (see table above). It is typically seen in patients with long standing bronchial asthma. The most characteristic radiologic finding is the presence of bronchiectasis of segmental and primary subsegmental bronchi, usually in the upper lung segments, with mucous impaction. In a chest radiograph these impacted bronchiectasis display as hyperdense t Some type of ELD have characteristic radiologic findings. However, others either don't have specific radiologic characteristics or share similar morphologies which makes them hard to distinguish. Therefore, it is critical to know the associated analytic and pathologic findings to give a correct diagnosis[i]. For example, in patients with chronic asthma there are three different types of ELD: Bronchopulmonary aspergillosis, allergic vasculitis and chronic eosinophilic pneumonia. The allergic Bronchopulmonary aspergillosis (ABPA) is one of the ELD of known cause (see table above). It is typically seen in patients with long standing bronchial asthma. The most characteristic radiologic finding is the presence of bronchiectasis of segmental and primary subsegmental bronchi, usually in the upper lung segments, with mucous impaction. In a chest radiograph these impacted bronchiectasis display as hyperdense tubular structures with homogenous margins in a bronchial distribution, also called "finger-in-glove" sign (figure 2). In HRCT the same findings are present (figure 3). In 30% of cases there can be some calcification and therefore high attenuation of the impacted mucus. Sometimes, it can be associated with lobar atelectasis. Bronchoalveolar lavage (BAL) shows important eosinophilia and can include hyphal fragments. Those help to differentiate between ABPA and bronchiectasis of different origin[ii]. Other ELD associated with asthma are the Churg-Strauss' Syndrome (CSS) and chronic eosinophilic pneumonia (CEP). In both syndromes BAL shows important eosinophilia (>30%) and more than 10% eosinophilic granulocytes in differential white cell blood count. In addition, the radiologic findings are also similar, yet, they are considered Page 4 of 16

5 as a differential diagnosis of one another. In both diseases, predominant peripheral consolidations are typical findings. In CSS consolidations tend to show a lobular distribution, whereas in CEP interlobular fissures are not respected. CSS can also be accompanied by centrilobular nodules and subpleural groundglass opacity [iii] (figure 4). CEP, in contrast, typically shows homogenous peripheral airspace consolidation that can display as a "negative edema" on the chest radiograph (figure 5). CEP and CSS differ in that the latter is associated with extrapulmonary manifestations such as paranasal sinus anomalies, neuropathy and extravascular eosinophilia in muscle or nerve biopsy. The pathology can affect every organ, however, it involves lung and skin most frequently. Histological examination can also help differentiating between both diseases. CEP is characterized by alveolar eosinophilic infiltration and fibrotic changes, whereas CSS can show signs of vasculitis and necrotizing granulomatosis. CSS is a serious and potentially life threatening disease because necrosis due to the vasculitis can lead to infarction in different organs including cardiac muscle. Upon diagnosis immunosuppressive therapy is essential. Radiologic findings such as transient or changing thoracic opacities are also seen in Loeffler s syndrome which is also known as simple eosinophilic pneumonia. Loeffler's syndrome, in contrast to CEP and CSS, is a benign entity. The most characteristic findings are changing infiltrates (figure 6 and 7). Typically, chest radiographs show unilateral or bilateral consolidations that often disappear spontaneously within one month. In HRCT fluctuant airspace consolidations, sometimes in combination with transient nodules and surrounding ground-glass opacity, are suspicious for simple eosinophilic pneumonia, especially in young patients with no underlying disease and blood eosinophilia[iv]. Histological correlation is eosinophilic granulocytes and edema in septa and interstitium. Blood eosinophilia occurs but, typically, patients show few or no respiratory symptoms. Underlying Aspergillus infection, parasitosis or drug toxicity have to be excluded before diagnosing Loeffler's syndrome. One severe pathology is the acute eosinophilic pneumonia (AEP). It is considered to be idiopathic, although some scholars discuss its relation to inhalations of dust or smoke[v]. The diagnosis is as difficult as important because high dose steroids can prevent the patient from respiratory insufficiency. The problem with diagnosing AEP is that clinical and radiologic findings resemble those of an infectious disease. Patients show high fever, hypoxia and diffuse alveolar or alveolar-interstitial infiltrations. The imaging findings often remind of acute interstitial pneumonia or viral infection. It can also impress as pulmonary edema or acute respiratory distress syndrome. Most characteristic findings are bilateral reticular infiltrates, with or without patchy opacification, and pleural effusion. In addition, it is the only eosinophilic lung disease without blood eosinophilia, what makes the correct diagnosis even more difficult. The BAL in contrast shows high levels of eosinophilic granulocytes with up to 25%. When treated with high dose steroids the symptoms Page 5 of 16

6 disappear within h and no relapse is seen, in contrast to chronic eosinophilic pneumonia. Therefore, early diagnosis is critical. Another less acute, but life threatening pathology is the idiopathic eosinophilic syndrome. It is a rare disease, seen especially in middle aged male. A large amount of eosinophilic granulocytes with up to 1500 per cubic millimeter and persistence for at least 6 month is characteristic. Damage in multiple organs, with major involvement of the heart and central nervous system results from the intense infiltration of these organs with eosinophilic granulocytes. The changes appearing on thoracic images result mostly from cardiac failure following severe valvular damage, endocardial fibrosis or restrictive cardiomyopathy. Therefore, the findings are non specific. Those include bilateral alveolar opacities and pleural effusions due to pulmonary edemas (figure 6). CT can show nodules with surrounding ground glass opacity, similar to Loeffler's syndrome. Most patients die from cardiac failure. In all the pathologies discussed above, especially in simple eosinophilic pneumonia, eosinophilia of known origin has to be excluded. One of the classic causes of eosinophilia is parasitic infection, although rare in the western world. We want to stress that the radiolgist needs to remember that a patient with eosinophilia and disorders in thoracic imaging could suffer from parasitosis. Parisitosis can affect the lung in two different ways. One is the direct invasion of the lung parenchyma by the parasite seen in infection with Ascaris, Filaria or Schistosoma. The other one is an allergic reaction to the parasite, such as in Entamoeba histolytica,toxocaracanis or Clonorchissinensis. Imaging findings vary with the different species. To discuss all imaging findings in every parasite is beyond the scope of this poster. Shistiosomasis is a representative example. In this parasitosis, characteristically, the parasite nests its eggs directly in the patient's lung. Granuloma formation and fibrotic changes surrounding the eggs can be seen and a complication is the obstruction of blood vessels by the eggs resulting in pulmonary hypertension. History of recent travels to Africa, Asia or South America can lead to the diagnosis of parasitosis. Immunologic tests should be performed in order to exclude such disease. Finally, if imaging findings are non specific, they vary between consolidations, nodule formation or areas of ground-glass opacity, the radiologist needs to be aware that eosinophilic pneumonia can be a side effect to different drugs. Once this origin is known, it is relatively easy to treat. In most cases the stop of medical treatment makes the symptoms and thoracic disorders disappear. Diagnosis is often made by laboratory tests. Therefore, patients with eosinophilia and changes in thoracic imaging should be scanned for recent onset of new medical therapy. Page 6 of 16

7 Images for this section: Fig. 1: Table with overview of the different types of eosinophilic lung diseases of known and unknown origin Page 7 of 16

8 Fig. 2: Brochopulmonary Aspergillosis; Chest radiograh showing bronchiectasis of segmental and primary subsegmental bronchi with mucous impaction. "Finger-in-glove" sign. Page 8 of 16

9 Fig. 3: HRCT or Bronchopulmonary Aspergillosis; hyperdense tubular structures with homogenous margins in a bronchial distribution. Page 9 of 16

10 Fig. 4: Subpleural groundglass opacity Page 10 of 16

11 Fig. 5: CEP: homogenous peripheral airspace consolidation that can impress as "negative edema" on chest radiograph. Page 11 of 16

12 Fig. 6: Signs of pulmonary edema due to cardiac failure in patient with IHS. Page 12 of 16

13 Fig. 7: Loeffler`s syndrome: Changing infiltrates. Young female patient in September 2012 Page 13 of 16

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15 Fig. 8: Loeffler`s syndrome: Changing infiltrates. Young female patient in December Page 15 of 16

16 Conclusion Radiologists have to know ELS because in the most severe case of acute eosinophilic pneumonia an early diagnosis is critical in order to start the correct treatment and avoid severe consequences. In the context of pneumonia with neither response to the normal treatment nor underlying malignancy, eosinophilic pneumonia should be at least considered. Good communication between radiologist and clinician is essential because imaging findings often overlap so that diagnosis can only be made in light of additional analytic and pathologic findings. Personal information References [i] Yeon Joo Jeong and others, 'Eosinophilic Lung Diseases: A Clinical, Radiologic, and Pathologic Overview', Radiographics: a review publication of the Radiological Society of North America, Inc, 27 (2007), ; discussion <doi: / rg >. [ii] T Franquet and others, 'Spectrum of Pulmonary Aspergillosis: Histologic, Clinical, and Radiologic Findings', Radiographics: a review publication of the Radiological Society of North America, Inc, 21 (2001), <doi: /radiographics.21.4.g01jl03825>. [iii] Eva Castañer and others, 'Imaging Findings in Pulmonary Vasculitis', Seminars in ultrasound, CT, and MR, 33 (2012), <doi: /j.sult >. [iv] T Johkoh and others, 'Eosinophilic Lung Diseases: Diagnostic Accuracy of Thin-Section CT in 111 Patients', Radiology, 216 (2000), <doi: / radiology r00se01773>. [v] William N Rom and others, 'Acute Eosinophilic Pneumonia in a New York City Firefighter Exposed to World Trade Center Dust', American journal of respiratory and critical care medicine, 166 (2002), <doi: /rccm oc>. [vi] Jeong and others. Page 16 of 16