Intralobar Pulmonary Sequestration

General: Pulmonary parenchyma within the normal pleura but still isolated from the tracheobronchial tree and normal pulmonary vasculature, usually supplied instead by pulmonary ligament arteries. The vast majority are not found in newborns or associated with other malformations, but are considered acquired. Limited to the lower lobes in ~98% of cases, and ~85% of patients have a history of chronic or recurrent pneumonias. Roughly equivalent incidence, though left > right.

Gross: May demonstrate variably thickened pleura, if present, with adhesions to adjacent structures. May have variably sized (1mm - ~5cm) cysts with thin to viscid fluid.

Microscopic: Dense fibrous parenchyma with pulmonary component often further distorted by chronic inflammation. Cysts are lined by cuboidal or columnar epithelium and filled with amorphous eosinophilic material and/or foamy macrophages. Arteries are present and may show medial hypertrophy, thrombosis, and/or arteritis.

Stains:

• Positive:
• Negative:
• Suggested, focused panel:

((())) Stocker's Pediatric Pathology, 2001

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