SECTION EDITOR: C. DOUGLAS PHILLIPS, MD
Diagnosis: Primary tracheal amyloidosis
Isolated tracheobronchial amyloidosis is an extremely rare entity, representing less than 1% of all cases of amyloidosis, with fewer than 150 cases reported in the literature.1 The precise pathogenesis remains elusive, although the disease is hypothesized to be of plasma cell origin via overproduction and deposition of AL amyloid into tracheobronchial tissue.2 Presenting symptoms are nonspecific, as in the present case, making the diagnosis more challenging. Three patterns of the disease have been described according to the location of the amyloid deposition: proximal, middle, and distal airway involvement, corresponding to the distal trachea, carina, and proximal mainstem bronchi, respectively.1 A fourth “diffuse” pattern has also been reported, with amyloid involvement in all 3 areas.3 The pattern of amyloid deposition has been shown to be predictive of the presenting symptoms. Proximal disease is associated with generalized signs of upper airway obstruction such as stridor and hoarseness. Middle and lower airway variants may present with chronic cough, hemoptysis, repeated pneumonia, or asthmalike symptoms.1,4 There appears to be little to no association between tracheobronchial and systemic amyloidosis. In the largest series with long-term follow-up, O’Regan et al1 found that none of the cases that presented with primary tracheobronshial amyloidosis progressed to systemic amyloidosis, nor did tracheobronchial amyloidosis develop in cases that presented with systemic amyloidosis over the 15-year duration of their study.
Radiology Quiz Case 3: Diagnosis. Arch Otolaryngol Head Neck Surg. 2011;137(9):960. doi:10.1001/archoto.2011.150-b