Chylothorax as presenting manifestation of adenocarcinoma with probable gastric primary. Chylothorax is an unusual complication of various malignant neoplasms, generally lymphomas. The few reported cases of chylothorax with gastric and other abdominal malignancies have involved large abdominal masses with prominent adenopathy and chylous ascites. We describe a patient in whom chylothorax was the presenting manifestation of an adenocarcinoma with probable gastric primary, developing prior to any clinical or radiologic evidence of tumor. 