Chronic interstitial pneumonitis is a broad descriptive term where an interstitial pneumonia has a prolonged course. It can arise from a range of etiologies. The term does not usually imply a specific radiographic pattern and includes UIP, NSIP or other patterns. As a general rule, there is little or no ground glass or confluent consolidation with more reticulation. Some authors place all interstitial pneumonias other than acute interstitial pneumonia into this group.