Intra-abdominal sequestration of the lung and elevated serum levels of CA 19-9: a diagnostic pitfall.

BACKGROUND: Extralobar pulmonary sequestration is an uncommon congenital abnormality that is rarely diagnosed after the age of 40 years. We describe a 64-year-old woman with an intra-abdominal sequestration of the lung and elevated carbohydrate antigen (CA) 19-9 serum levels. CASE OUTLINE: On abdominal ultrasound a semi-solid cystic tumour was demonstrated that showed tight connection to the tail of the pancreas according to computed tomography. Cytological examination of the percutaneous biopsy did not lead to a definitive diagnosis. CA 19-9 serum levels were repeatedly elevated >250 IU/ml. With a tentative diagnosis of a tumour of the tail of pancreas the semi-solid cystic mass was resected. Frozen section histology suggested the diagnosis of pulmonary sequestration, which was confirmed by definitive histological examination. Immunohistochemical staining of the specimen with a specific monoclonal antibody against CA 19-9 showed strong immunoreactivity. Three months later the elevated CA 19-9 serum levels returned to normal. DISCUSSION: Elevated CA 19-9 serum levels have been described in benign pulmonary and mediastinal cystic lesions and in one case of extralobar intrathoracic lung sequestration. Although there is evidence that malignancies may arise in congenital lung cysts, CA 19-9 serum levels have not been investigated in such cases. Based on our results elevated serum values of CA 19-9 in combination with a cystic semi-solid mass in the left subphrenic space should include the differential diagnosis of extralobar pulmonary sequestration.