The pulmonary sequestration corresponds to pulmonary tissue intra or extra-lobar with systemic arterial nutrition and collateral bronchial ramification. It is infrequent and the intra-lobar identification depends on the correct clinical signs and morphology. The correct study includes imagiologic identification of the systemic artery and morphological characterization of parenchymal changes. These allow identification of abnormal pulmonary parenchyma in intra-lobar cases and were observed using histochemical and immunohistochemical routine methods, both in intra and extra-lobar cases. Four cases of intra-lobar sequestration and four cases of extra-lobar sequestration were studied with application of histochemical techniques--Movat's pentachrome stain and Verhoeff--and immunolabelling with CK7 and TTF1. The parenchymal inflammatory distortion by collagenization was constantly seen as was BALT hyperplasia and pleuritis. By using Movat's pentachrome stain we characterized the sequestration by identifying the artery and the parenchymal changes. The CK7 was useful in the identification of parenchymal damage, together with the antibody anti-TTF1 that had a variable expression, stronger in areas of inflammation because of PII hyperplasia.