Inflammatory pseudotumor of the lung in children.

Two children with inflammatory pseudotumor (IPT) of the lung are reported. Symptomless "cystic" lesions were present on routine chest x ray. Morphological study of these peculiar lesions included light microscopic, immunohistochemical, and ultrastructural analysis. Histologic appearance of the lesion varied from the features of granulation tissue on the periphery to bundles of spindle-shaped cells in the central area. Immunohistochemical findings had no diagnostic value but were helpful in excluding other tumors. Ultrastructural analysis confirmed the mixed cellular composition and benign nature of the lesion. Etiopathogenesis of this process is unknown. IPT can be differentiated from similar lesions and must not be mistaken for malignant tumor. Proper treatment by complete surgical removal of the lesion usually cures the patient.