Usual interstitial pneumonitis (UIP):
Chapter: 12
The most common type of idiopathic chronic interstitial pneumonitis, characterized clinically by progressive respiratory insufficiency and pathologically by interstitial inflammation and fibrosis. Clinically, UIP begins insidiously with gradual onset of dyspnea and cough. Pathologically, UIP is an inflammatory and fibrosing lesion affecting predominantly the interstitium. The single most important histologic finding that separates UIP from other interstitial pneumonias is the marked variation from field to field in degree of lung involvement and also in the nature and appearance of the cellular infiltrate.