Pleural effusions with high amylase levels are reported frequently in patients with pancreatic diseases, a rupture of the esophagus and a malignancy. However, there is no data available on the clinical features of an amylase-rich pleural effusion in Korea. This report describes the causes of the high amylase levels in a pleural effusion and analyzes its association with malignancy.

The records of patients with an amylase-rich pleural effusion who were assessed at the Gyeongsang National University Hospital from January 1998 to August 2002 were examined retrospectively, and the distribution of amylase levels in those patients, the causative diseases, and the histological type in the case of a malignancy were analyzed. Among the 532 patients whose pleural effusion was evident on a chest X-ray, there were 36 cases with an amylase-rich pleural effusion. The amylase levels were determined by an enzyme method (Hitach 747 autoanalyzer).

Of the 36 patients with an amylase-rich pleural effusion, there were 18 patients(50%) associated with a malignancy, 8 patients(22%) with a parapneumonic effusion, 7 patients(19%) with pancreatic disease, and 3 patients with other causes. The amylase level in a pleural effusion due to pancreatic disease was much higher than that due to other causes(p<0.01). Among the malignant pleural effusions with high amylase levels, the origin of the malignancy was a primary lung cancer in 13 cases and metastatic lung cancer in 5 cases. The histological types of malignant causes were adenocarcinoma in 10 cases(56%), squamous cell carcinoma in 2 cases(11%) and unknown type of carcinoma in 6 cases. The amylase level in the adenocarcinoma cases was much higher than that in the other cell type carcinomas(p<0.01). There was no significant association between the amylase level and the glucose level among the malignant cases with amylase-rich pleural effusion(p=0.21).

The most frequent cause of an amylase-rich pleural effusion was a malignancy. Primary lung cancer and adenocarcinoma were the most common malignancies and histological types associated with a malignant pleural effusion with high amylase levels. The amylase level in a pleural effusion secondary to pancreatic disease was much higher than from any other causes.