Tracheobronchial Amyloidosis

Radiology

Figures 1 & 4 are from one patient and figures 2 & 3 are from another.

Figure 1. Trachea, Lung Window: In the airway, amyloid deposition may appear as single or multiple nodules.

nodule1nodule2nodule2nodule3

 

Find 3 nodules in the trachea.

 

Tracheobronchial amyloidosis does not spare the posterior tracheal membrane (unlike tracheobronchopathia osteochondroplastica; scroll down to the bottom), and is not associated with airway malacia on expiratory imaging.

Figure 2. Trachea, Soft Tissue Window: Amyloid may also appear as diffuse, airway thickening, as in this example from another patient. The deposits may calcify or ossify.

trachea

 

Find the thickened, calcified or ossified trachea.

 

bronchus

Figure 3. Bronchi, Soft Tissue Window

Note the dense calcifications in the thickened left and right main bronchi and their branches.

Find the thickened, calcified or ossified left main bronchus.

Figure 4. Bronchi, Lung Window: This image at the level of the right lower lobe bronchus shows concentric airway thickening with areas of increased attenuation representing calcification.

bronchus1bronchi2calc1calc2

 

Find 2 thickened middle lobe bronchi.

Find 2 calcifications within the walls of the right basilar bronchi.


Pathology

Figure 5. Histologic Changes: With the exception of the cartilages, the entire wall of the trachea is replaced by amyloid. Small vessels remain within the amyloid.

The bluish areas adjacent to the cartilages represent cartilaginous metaplasia in the amyloid. Such foci may ossify.

cart1cart2cart3

 

Find 3 foci of cartilaginous metaplasia.

 

Figure 6. Ultrastructure

This picture from another case shows the typical ultrastructure of amyloid: randomly-oriented, non-branching fibrils, 7.5-10 nm in diameter, of indeterminate length.

Electron microscopy is usually reserved for cases in which the stains at the light microscopic level are non-diagnostic or for cases with minimal deposits, as in the kidney. All amyloids have a similar ultrastructure.

References

1. O'Regan A, Fenlon H, Beamis J Jr, Steele M, Skinner M, Berk J. Tracheobronchial amyloidosis. The Boston University experience from 1984 to 1999. Medicine 2000; 79:69-79. Abstract

2. Tracheobronchial amyloidosis. Capizzi SA, Betancourt E, Prakash U. Mayo Clin Proc 2000; 75:1148-1152. Abstract

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Tracheal nodule

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Thickened trachea

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Calcified or ossified left main bronchus

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Focus of cartilaginous metaplasia within the amyloid

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Middle lobe bronchus with thickened wall and narrowed lumen

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Calcification within thickened bronchial wall, right basilar bronchus

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