Pulmonary amyloidosis occurs in 3 forms: tracheobronchial, parenchymal, and alveolar-septal.9 Primary TBA, although the most frequent among forms of pulmonary amyloidosis, is considered a rare disease. It is characterized by a slow and progressive deposition of amyloid material in the submucosa that could lead to airway obstruction, hemoptysis, chronic cough, and recurrent airway infections.4,5 Typically, it affects men more often than women and occurs in the fifth or sixth decade of life.1,2
Besides unspecific bronchoscopic findings while using white light as mucosal irregularity and redness,3 other lesions have been reported in TBA as “characteristics” including multiple submucosal plaques and solitary amyloid deposits having a nodular or tumor-like appearance suggestive of endobronchial neoplasms.2,4,10
Premalignant and malignant lesions can cause a variety of mucosal changes in the trachea and bronchi. Angiogenesis, a relatively early event during lung cancer pathogenesis, is often difficult to see with white light bronchoscopy. NBI bronchoscopy is useful enhancing fine superficial microvessel patterns of mucosal vascularity when incipient neoplastic processes occur in the airway.6–8 Also, NBI has shown utility for diagnosing benign diseases as hereditary hemorrhagic telangiectasia.11 A good sensitivity and specificity of NBI has been reported on early detection of lung cancer6,8,12 when 3 or more of the following criteria are present during bronchoscopic examination: capillary loops, dotted vessels, complex vascular networks of tortuous vessels, and abrupt-ending vessels. These findings, suspicious for intraepithelial neoplasm, are histologically correlated with the presence of moderate dysplasia, severe dysplasia, carcinoma in situ, and invasive carcinoma.12,13
Hui et al,14 with the help of NBI and magnifying endoscopy, described a greyish-green appearance of the nodules that infiltrate the mucosa in rectal amyloidosis without evidencing vascular changes that are present in colorectal cancer. This is probably related to amyloid deposits in the lamina propia. In the 2 cases presented, visualization of the mucosa with white light and high-resolution bronchoscopy allowed for the identification of changes already described in TBA, which are unspecific. Nodules, mucosal irregularity, and blurred cartilages presented in these cases could be considered suspicious of neoplasm when using white light.3,12
During NBI examination, 3 vascular patterns were observed in each case: capillary loops, complex vascular networks of tortuous vessels, and abrupt-ending vessels, leading to the suspicion of intraepithelial neoplasm. Interestingly, dotted vessels that were not found in these particular cases are associated with a major degree of angiogenesis and malignant invasion.13,15
Small septal and perivascular deposits of amyloid could be found by histopathology. Mucosal epithelium could remain intact or present changes of squamous metaplasia.16 Diffuse amyloid infiltration of the submucosa could involve glands and cartilage. It is probable that various degrees of epithelium metaplasia and vascular obstruction due to perivascular deposits of amyloid are responsible for the origin of collateral vessels and vascular patterns found in TBA.
Various changes in the tracheobronchial mucosa that are secondary to amyloidosis could suggest a neoplastic origin when the airway is exanimated using white light and NBI bronchoscopy. Indirect findings suggestive of neoplasm as mucosal irregularity, blurred cartilages, redness, and edema, as well as direct findings as endobronchial tumor could be evidenced during white light examination. We have found at least 3 vascular patterns suggestive of angiogenesis when performing NBI examination in TBA. Both white light and NBI bronchoscopic findings in TBA could mimic those findings suggestive of intraepithelial neoplasm. Definite diagnosis will be established only by histopathology analysis.
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Keywords:© 2014 by Lippincott Williams & Wilkins.
bronchoscopy; tracheobronchial amyloidosis; white light; narrow-band imaging