Set 1: interstitial vs alveolar

55 year old male with shortness of breath, history of heart failure

There are many fine criss-crossing lines in this patient’s lung, some extending far out into the periphery, where there are normally no markings.  This is an example of an INTERSTITIAL pattern.  The abnormal markings are relatively crisply defined and can be described as ‘linear’ or ‘reticular’, meaning crossing lines (like chickenwire or netting).