Part of the family of idiopathic interstitial pneumonias, but lacks the histopathologic features to specifically classify the disease. Patients typically present with the subacute development of dyspnea and cough. Other presenting symptoms such as Raynaud phenomenon, dry mouth or eyes, or rash or skin changes may point to an underlying collagen-vascular disease. Physical examination typically reveals bibasilar crackles.

While there is no definitive cause, there are associations with collagen-vascular diseases including polymyositis-dermatomyositis, rheumatoid arthritis, Sjögren syndrome, and systemic sclerosis, infections such as human immunodeficiency virus (HIV), and medications such as flecainide, amiodarone, methotrexate, carmustine, nitrofurantoin, statins, and chlorambucil.