Idiopathic<unk>  pneumonias are broad subsets of pulmonary diseases due to unidentifiable causes. Therefore, the diagnosis of idiopathic pulmonary pneumonia should lead to a careful clinical workup for the known etiological factors and possible adverse drug reaction before Idiopathic<unk>  pneumonia is diagnosed.
The most common collagen vascular disease in the lung that should be excluded first are
Rheumatoid arthritis
Systemic lupus erythematosus
Sjögren's syndrome
Polymyositis
Dermatomyositis
Progressive systemic sclerosis
Mixed connective tissue disease.
Idiopathic interstitial pneumonia causes
Hypersensitivity pneumonitis causes
Eosinophilic pneumonia causes
Lymphomatoid granulomatosis causes
Idiopathic pulmonary fibrosis causes
Pneumoconiosis causes
Hypersensitivity pneumonitis risk factors
Lipoid pneumonia causes