REVIEW OF PATHOLOGY Questions Chapter 15. The Lung Hypersensitivity pneumonitis is a type Ill (and type IV) hypersensitivity response to an inhaled allergen. Pulmonary alveolar proteinosis is a rare idiopathic condition in which there are gelatinous alveolar proteinaceous exudates. Wegener granulomatosis is a form of vasculitis with pulmonary capillaritis. (PDF) Scleroderma and pulmonary hypertension to be direct involvement of the pulmonary circulation with intimal proliferation and medial hypertrophy, somewhat similar to that seen in primary pulmonary hypertensi- Types, Causes and Risk Factors of Pulmonary Fibrosis Pulmonary fibrosis (PF) is a form of interstitial lung disease that causes scarring in the lungs. There are over 200 different types of PF and in most cases, there's no known cause. Here's a look at some of the different categories of PF.