A rare case of bilateral chylothorax: a diagnostic challenge--follicular lymphoma versus primary effusion lymphoma.

Chylothorax is most common on the left side owing to the position of the thoracic duct. Malignancy-associated chylothorax is not uncommon. However, bilateral chylothorax is rare and malignancy should be a consideration in absence of trauma. We report a case of a patient with follicular lymphoma who presented with bilateral pleural effusion; pleural fluid analysis confirmed chylothorax. The patient did not have any significant peripheral or axial lymphadenopathy, which made the diagnosis difficult in absence of histopathology. Pleural fluid analysis was negative for malignant cells, however, the flow cytometry markers were suggestive of follicular lymphoma. Primary effusion lymphoma, which could have been another possibility, was ruled out by the flow cytometry markers. We conclude that pleural fluid flow cytometry markers play an important role where there is no significant lymphadenopathy and in absence of histopathological diagnosis. This demands further evaluation.