Middle lobe syndrome: an intriguing presentation of tracheobronchial amyloidosis

Abstract

Pulmonary involvement in amyloidosis is a distinct rarity. This clinical entity usually presents as tracheobronchial amyloidosis (TBA). A 32-year-old, never-smoker man presented with episodic dyspnoea and wheezing along with cough and mucoid sputum. The chest radiograph was suggestive of a middle lobe syndrome (MLS). High-resolution CT (HRCT) of the chest confirmed the presence of MLS. In addition, HRCT showed circumferential thickening of the trachea and the main bronchi, with thickening of the posterior membranous wall of trachea. Fibrebronchoscopy, done to evaluate MLS, visualised multiple small polypoidal lesions in the lower part of trachea and carina. Endobronchial biopsies showed homogeneous, acellular amorphous deposit in the subepithelial region, which was congophilic in nature. A diagnosis of TBA presenting as MLS was made. To the best of our knowledge, this is the first detailed report of MLS as a presentation of TBA in the English literature.

A case of tracheobronchial amyloidosis with emphasis on differential diagnosis

“…The symptoms depend on which part of the tracheobronchial tree is affected. Accordingly, tracheobronchial disease is distinguished into three types: proximal (affecting the subglottic space and trachea), mid-(affecting the primary bronchi) and distal (affecting the outer airways) [1,2]. More specifically, when the proximal/upper trachea is affected, the presenting symptoms relate to upper airway obstruction.…”

“…Amyloid protein deposition may result in endobronchial obstruction. Moreover, it may cause dilation of the trachea [2,4,5]. At bronchoscopy, the entire endobronchial lumen may be involved (without sparing the posterior membrane).…”

Amyloidosis and the Lungs and Airways

“…Presenting symptoms include dyspnoea, persistent cough, wheeze, haemoptysis, chest tightness and hoarseness (143). Deposits may cause distal atelectasis, recurrent pneumonia or lobar collapse (144) and solitary nodules may be mistaken for neoplasia (145) although 70% of a series had normal radiography (146). Typically deposits have intermediate T1 weighted signal intensity on MRI and low T2 weighted signal intensity similar to skeletal muscle (121).…”

Middle lobe syndrome: An exceptional presentation of concomitant lepidic adenocarcinoma and bronchial anthracofibrosis

“…MLS is usually due to enlarged peribronchial lymph nodes, endobronchial mass or infective aetiology including bronchiectasis [17]. The other uncommon causes of MLS include BAF [15], allergic bronchopulmonary aspergillosis [18], endobronchial tuberculosis [19], pulmonary hydatid [20] and tracheobronchial amyloidosis [21]. Chest radiograph is the initial diagnostic modality for MLS and it presents as a homogeneous opacity abutting the right cardiac border with a loss of cardiac silhouette.…”