[Extrinsic allergic alveolitis in children. Apropos of 4 cases]

Four cases of extrinsic allergic alveolitis are reported. About them, we discuss: The difficulties of diagnosis that we can only affirm on the association of several clinical, biological, and radiological arguments. The physiopathology: association of immune complex hypersensitivity type III and immediate hypersensitivity type I. It's important to always search for a probable starting infectious factor (mycoplasma). The therapy: antigenic exclusion is the only way to avoid a lung fibrosis.