This case has been tagged as "legacy" as it no longer meets image preparation and/or other case publication guidelines.
From the case:
Pulmonary sarcoidosis
Axial lung window

Perilymphatic nodules are interstitial nodules (usually well-defined) which are characterized by distribution. Nodules are subpleural, along fissures, along interlobular septa, and adjacent to the bronchovascular bundles.
Case Discussion
The differential diagnosis of nodules in a perilymphatic distribution is limited :
- the most common cause is sarcoidosis (typically symmetrical and upper lobes)
- also common is lymphangitis carcinomatosis (often asymmetrical and lower lobe)
- silicosis
- coal workers' pneumoconiosis uncommonly give this appearance
- rare causes include amyloidosis and lymphocytic interstitial pneumonitis
In this case the diagnosis was sarcoidosis.