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|Year : 2013 | Volume
| Issue : 3 | Page : 223-225
Primary tracheobronchial amyloidosis: Coronal CT scan may provide clues for early diagnosis
D Li1, Z Shi1, Y Wang2, A Thakur1
1 Department of Respiratory and Critical Care Medicine, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi, China
2 Department of Medical Imaging, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi, China
|Date of Submission||22-Jul-2012|
|Date of Decision||28-Feb-2013|
|Date of Acceptance||30-May-2013|
|Date of Web Publication||12-Sep-2013|
Department of Respiratory and Critical Care Medicine, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi
Source of Support: This work has been supported in part by the National Natural Science Foundation of China (Grant No. 81270094) and the Youth Innovation Foundation of First Affiliated Hospital of Xi’an Jiaotong University (Grant No. 2009YK07), Conflict of Interest: None
Primary tracheobronchial amyloidosis (PTBA) is a localized form of amyloidosis. The clinical signs of this condition are non-specific and diagnosis before bronchoscopic examination with multiple biopsies is uncommon. We present three cases of PTBA and compare findings between the thoracic imaging and fiberoptic bronchoscopy. Radiographic findings often had uncharacteristic features. The relatively specific coronal section CT preceded findings in transverse sections, and showed an irregular mucosal surface with diffuse prominent nodes and/or calcification of the tracheobronchus, which we called the "wavy path sign". In conclusion, coronal CT scan can provide ample clues for the early diagnosis of PTBA.
Keywords: Amyloidosis, bronchoscope, coronal CT scan, tracheobronchus
|How to cite this article:|
Li D, Shi Z, Wang Y, Thakur A. Primary tracheobronchial amyloidosis: Coronal CT scan may provide clues for early diagnosis. J Postgrad Med 2013;59:223-5
|How to cite this URL:|
Li D, Shi Z, Wang Y, Thakur A. Primary tracheobronchial amyloidosis: Coronal CT scan may provide clues for early diagnosis. J Postgrad Med [serial online] 2013 [cited 2020 May 28];59:223-5. Available from: http://www.jpgmonline.com/text.asp?2013/59/3/223/118045
| :: Introduction|| |
Amyloidosis is the infiltration of multiple organs by amorphous extracellular eosinophilic material. Secondary systemic amyloidosis is usually due to neoplastic or chronic inflammatory processes.  Amyloid deposition restricted to the respiratory system is termed primary pulmonary amyloidosis (PPA). This uncommon disease presents in three histopathological types: Tracheobronchial, nodular, and diffuse parenchymal.  Definitive diagnosis requires detection of amyloid, which demonstrates characteristic green birefringence on biopsy specimens stained with Congo red and viewed under polarizing microscope. , In the early stage, patients with primary tracheobronchial amyloidosis (PTBA) have non-specific respiratory symptoms and are reluctant to undergo invasive bronchoscopic examinations, which make definitive management difficult for clinicians. Radiological findings in PTBA show narrowing of the distal trachea and the main bronchus with irregular surfaces. Characteristic CT findings are only reported for the transverse section and described as circumferential thickening of the mucosal wall, substantial narrowing of the main, lobar, and segmental bronchi, calcification of the trachea and central bronchial tree, sometimes along with bronchiectasis, atelectasis, post-stenotic pneumonia, and lumpy calcified mass in the mediastinum. ,,, Here, we present three cases of PTBA with no evidence of systemic amyloidosis (rheumatoid arthritis, tuberculosis, Hodgkin's disease, Crohn's disease, etc.) or multiple myeloma, then discuss how the "wavy path sign" may provide preliminary clues of PTBA on coronal CT sections eventually confirmed by bronchoscopy.
| :: Case Reports|| |
A 78-year-old man was referred to our department with progressive dyspnea for 6 months. The patient had experienced hemoptysis for 20 days with a predominant inspiratory stridor. A lung function test revealed obstructive dysfunction of pulmonary ventilation with severe limitation of both peak inspiratory and expiratory flow rates. An axial chest CT showed circumferential thickening of the trachea, major bronchus and lobar bronchi with narrowing of the lumen [Figure 1]. Fiberoptic bronchoscopy showed significantly thickened and vulnerable surfaces, accompanied by hyperplasic epithelium, multiple nodules of varying sizes in the mucosa, and circumferential edema of the tracheobronchial tree. Congo red staining displayed birefringence typical of amyloidosis under a polarizing microscope. Due to advanced age and other reasons, the patient refused further management.
|Figure 1: CT scan in transverse section showed circumferential thickening of the tracheal wall|
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A 43-year-old man was admitted to our department with chief complaints of hemoptysis and cough for 4 months. Physical examination, lung function test, and repeated chest radiographs were unremarkable. Transverse CT scan was normal [Figure 2]a, but the coronal section CT showed a completely irregular mucosal surface with prominent nodes in the right distal bronchi, which we named "wavy path sign" [Figure 2]b. Fiberoptic bronchoscopy (which the patient had refused earlier) revealed a completely irregular and thickened bronchial mucosa surface with prominent nodes accompanied by whitish membranes, the so-called "rock garden appearance." The lumens of the right middle bronchus and right lower lobar bronchus were extremely narrowed. Congo red staining confirmed amyloidosis. With definite diagnosis, the patient received prednison therapy and all the symptoms partially resolved in a month.
|Figure 2: (a) CT scan in transverse section showed a normal setting; (b) However, in coronal section it demonstrated a completely irregular surface of the mucosa with prominent nodes in the right distal bronchi, which we called "wavy path sign"|
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A 60-year-old woman with 8 years of chronic obstructive pulmonary disease (COPD) history presented to our department with refractory cough, sputum, and increasing dyspnea on exertion for past 9 days. On physical examination, she had widespread stridor and wheezing. CT scan [Figure 3]a and b obtained 6 months earlier at a local hospital showed "normal findings". Six months later, a chest radiograph revealed right upper lobe (RUL) patchy opacity, and mediastinal deviation to the right. Both transverse and coronal CT scan showed circumferential lumens stenosis with prominent calcification of the trachea and the central bronchi, along with RUL atelectasis. A coronal CT revealed bilateral irregularity of the bronchial mucosa, with prominent nodes and calcification, that led to obstruction in some parts of the bronchi, and a more typical "wavy path sign" than that of case 2 [Figure 3]c and d. In fact, all observed signs, except atelectasis, could be seen to varying degrees on the previous CT scan. Fiberoptic bronchoscopy revealed multiple coalesced nodules in the walls of trachea and bronchi. The bronchial lumen appeared irregular and narrowed on bronchoscopic examination [Figure 4]a. Amyloid deposits were detected in the biopsy specimens [Figure 4]b. The patient was discharged without further systemic treatment in view of inability to pay for treatment.
|Figure 3: (a and b) 6 months ago, transverse CT scan showed circumferential wall thickening and calcification, and coronal CT section presented irregular surface of the mucosa with prominent nodes of bilateral main bronchi; (c and d) Current CT scan demonstrated more severe signs, including atelectasis|
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|Figure 4: (a) Fiberoptic bronchoscope revealed multiple coalesced nodules in the walls of trachea and bronchi; (b) Submucosal deposits of amyloid were detected in bronchial biopsy specimens stained with Congo red (original, ×20)|
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| :: Discussion|| |
PTBA is an extremely rare entity, but the most common form of PPA.  The clinical features are uncharacteristic and common symptoms include dyspnea, cough, hemoptysis, and wheezing. This non-specific nature delays precise diagnosis of this disease by an average of 17 months. , Patients are mostly misdiagnosed and treated for asthma, recurrent pneumonia, tracheobronchitis, or COPD. The average life expectancy for PTBA is approximately 9 years, and the overall survival rate at 4-6 years is only 31-43%. Due to stenosis of the lumen of the tracheobronchial tree, patients often progress to post-obstructive pneumonia and ultimately die from respiratory failure. Therefore, early diagnosis of this disease is critical to improve the prognosis of patients.
Radiological findings in PTBA show narrowing of the distal trachea and the main bronchi with irregular surfaces. Characteristic CT findings are only reported for the transverse section and described as circumferential thickening of the mucosal wall, substantial stenosis of main airway, calcification of the trachea and central bronchial tree, sometimes accompanied by atelectasis and pneumonia. ,,, These are identical to those in our cases. Thus far, no studies have reported coronal CT manifestations, while in our cases we found "wavy path sign" on this section, which displayed diffuse multiple polypoid nodules in the trachea and main bronchi, and this feature may be more characteristic in PTBA. In case 2, the CT presentation is normal in the transverse section of the lung. However, the abnormal signs in the coronal CT section were suggestive for further fiberoptic bronchoscopy evaluation.
Fiberoptic bronchoscopy helps in the definitive diagnosis of PTBA. Nevertheless, after normal imaging findings, patients are often reluctant to undergo this procedure due to its invasive nature. The characteristic findings of this disease are described as diffuse nodules in the trachea and bronchi,  which may be different from those of endobronchial carcinoma (usually presenting as a single node). The walls of the trachea and bronchi appear irregular and hemorrhagic. The lumen of the airway is narrowed to varying degrees.  All of these features were present in our cases.
Although the transverse CT findings for PTBA are relatively specific to this disease, 50% of the patients display normal findings in these scans (as seen in case 2),  resulting in delays in conducting the fiberoptic bronchoscope. In both cases 2 and 3, the abnormal CT findings in the coronal section suggested the requirement of fiberoptic bronchoscope. In case 1, coronal section images were not obtained due to poor quality of the reconstructed single-slice CT scanning. Hence, we believe that the abnormalities shown in the coronal CT scan might precede those of the transverse section and could provide a non-invasive imaging technique to aid the early diagnosis of this rare disease.
Cumulatively, our findings recommend that the application of coronal section CT imaging among patients with features suggestive of PTBA could provide ample clues to determine whether further evaluation with fiberoptic bronchoscopy is warranted.
| :: Acknowledgment|| |
We thank "Editage" for assistance in manuscript writing.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
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