Lymphocytic interstitial pneumonitis and nonspecific interstitial pneumonitis

Nonspecific interstitial pneumonitis (NIP) and lymphocytic interstitial pneumonitis (LIP), with or without lymphocytic alveolitis, are poorly understood pulmonary complications of HIV infection. These disorders probably represent a spectrum of lymphoproliferative processes that overlap, rather than distinct illnesses. The clinical presentation, radiographic findings, and physiologic abnormalities in NIP and LIP are not specific and therefore require a biopsy for definitive diagnosis. The clinical course of these illnesses is generally favorable, even without specific treatment.