Diffuse pulmonary parenchymal amyloidosis is considered the least common form of pulmonary amyloidosis 6.
Unlike the nodular form, patients tend to be more symptomatic and often have symptoms of cough and shortness of breath. The most common presentation in this form tends to be progressive dyspnoea 4.
Histologically, amyloid deposits are demonstrated in the interstitial alveolar septae, especially around capillary vessels. Secondary involvement with inflammatory infiltrates can be seen.
The diffuse involvement usually associated with systemic conditions 6 and is sometimes seen in association with multiple myeloma
CT - HRCT chest
In the diffuse type, there are non-specific interstitial infiltrates, occasionally with superimposed alveolar infiltrates. Once established, these hardly change over time 4.
There is interlobular septal thickening as an accompanying feature 3. The diffuse form can also rarely coexist with large nodules.
The diffuse parenchymal abnormality may be mostly nodular, but diffuse inhomogeneous opacities may also be seen 4.
The affected areas can calcify or, rarely, show frank ossification, although this is much less common than the nodular form of the disease.
Treatment and prognosis
The diffuse type generally tends to carry a poor prognosis.
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