Which are the two types of pulmonary sequestrations?

• A. Extralobar and intralobar
• B. Intralobar and intrapulmonary
• C. Extralobar and intrapulmonary
• D. Extrathoracic and intrathoracic

Answer: (A)

Pulmonary sequestration is categorized by whether the sequestered tissue has its own pleural covering or shares the pleura with the normal lung. The two types are extralobar and intralobar. Extralobar sequestration sits outside the normal lung with its own separate pleural envelope and often lies in the chest wall or near the diaphragmatic surface, sometimes presenting in infancy. Intralobar sequestration is embedded within the normal lung and wrapped by the lung’s visceral pleura, sharing the same pleural lining as the adjacent lung tissue, and it typically presents later with recurrent infections. The other phrasings describe location (inside vs outside the thoracic cavity) or imply lobar boundaries rather than the crucial pleural relationship, so they don’t define the two main types.