From the Archives of the AFIP: Intralobar Sequestration

Radiologic-Pathologic Correlation

Abstract Introduction Postulated Pathogenesis Clinical Characteristics

Pathologic Features Histologic Features Radiologic Appearance

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Histologic Features

Intralobar sequestration is histologically characterized by extensive fibrosis, chronic inflammation, vascular sclerosis, and cystic changes that largely replace the pulmonary parenchyma (2). The lesion may sharply abut normal lung parenchyma or blend diffusely with it (2). A specimen will contain remnants of bronchi and bronchioles that are surrounded by fibrous connective tissue, lymphocytes, and lymphoid aggregates with germinal centers (Figure 8a) (2). The cysts seen at gross inspection are lined by cuboidal or columnar epithelium and are filled with amorphous eosinophilic debris or foamy macrophages (Figure 8b, Figure 8c) (2). Foci of acute bronchopneumonia may be present (2). The alveoli that border the normal lung parenchyma may be hyperinflated or emphysematous, and bronchiectasis may be present (1,26,36).

Elastic and muscular arteries within the lesion may demonstrate thrombosis, endarteritis, medial hypertrophy, and atherosclerosis (2). Atherosclerotic changes within the aortic branches that supply the sequestration are common, even in children (1,37). Pryce (3) observed that the degree of "atheromatous degeneration" within a systemic feeding artery was related to the severity of inflammation within the sequestration. Despite their origin from the systemic circulation, the arteries coursing into the lesion are chiefly composed of elastic rather than muscular elements, imitating the histologic characteristics of pulmonary arteries (1,3,30).

Numerous lamellated bodies within undeveloped dilated bronchioles have been identified in rare cases, when calcification is noted within the sequestration at radiography or CT (38,41). Intralobar sequestration has been reported to harbor squamous cell carcinoma or adenocarcinoma (in three patients, aged 36, 50, and 69 years), tuberculous infection, aspergillosis, and other unusual fungal species (30,42,43).

Abstract Introduction Postulated Pathogenesis Clinical Characteristics

Pathologic Features Histologic Features Radiologic Appearance

Therapy And Prognosis Conclusions Source Information References