Pulmonary sequestration--a diagnostic pitfall: a case report.

Pulmonary sequestration is defined as a congenital malformation of abnormal lung tissue that does not communicate with the airway system and that receives blood supply from anomalous arteries. The majority of these sequestrations are encountered in the pediatric population. Surgical excision is the treatment of choice, with excellent prognosis. We studied a case of an extralobar pulmonary sequestration in a young adult, presenting as an intrathoracic mass; it was aspirated twice, final diagnosis being rendered after surgical resection. The cytologic findings and the accompanying diagnostic difficulties to our knowledge have never been reported.