- Lymphoid interstitial pneumonitis (LIP)search for term
A type of pneumonia that affects 35 to 40% of children with AIDS, and which causes hardening of the lung membranes involved in absorbing oxygen. LIP is an AIDS-defining illness in children. The cause of LIP is not clear. There is no established therapy for LIP, but the use of corticosteroids for progressive LIP has been advocated.