Pulmonary pseudocysts (PPC) classically relate to chest trauma. It is a rare entity in adults, with multiple differential diagnosis. PPC most often evolve favorably. The clinical diagnosis is difficult to assess due to the poor and non specific clinical data. Chest radiographs are usually unsufficient for the diagnosis and the imaging modality of choice is computed tomography (CT). CT patterns of PPC relate to single or numerous cavities surrounded by air space consolidations. The physiopathological mechanisms of PPC remains uncertain. The histological study of this reported case affords some worth data to highlight the pathogenesis of this acquired abnormality.