Progressive Massive Fibrosis - PMF

Pathophysiology:  A complication of occupational inhalational lung diseases, typically silicosis.  Forms have been described with “coal workers’ pneumoconiosis”, and with asbestosis.  It is generally considered with silicosis.

The silica crystals (silicon dioxide) cause a non-caseating inflammation, with cell death and ensuing fibrosis.  The progressive lung fibrosis traps or engulfs the non-caseating granulomata in areas of fibrosis and amorphous proteinaceous material.  This leads to plaque-like or discoid lung masses.

CXR Findings:

1.      The typical changes of silicosis will have been present if older films are reviewed.

2.      Discoid plaque-like masses in the upper lungs, often bilateral and symmetrical.

3.      Associated lung fibrosis, lung nodules, and hilar traction often present.

4.      May have hilar adenopathy with egg shell calcification or underlying simple silicosis changes.

5.      Typical rim of emphysema around the PMF masses

Clues:  The major clinical issue is ruling out a lung cancer.  Tuberculosis may coexist with silicosis and may need to be excluded.  Get a clinical and occupational history.

“Aunt Sophies”:

1.      Primary lung cancer **

2.      Active tuberculosis *

3.      Post inflammatory scar (eg. old tuberculosis)

4.      Pleural plaqueing and fibrosis (eg. old infection, hemothorax, asbestos related pleural changes)