Pleural effusion in lymphoma

Pleural effusion in lymphoma is usually, but not invariably, a poor prognostic sign. The presence of underlying parenchymal lung involvement or a chylous type of effusion does not further alter the prognosis, but the presence of malignant cells in the fluid probably shortens survival. Obstruction of lymphatic drainage of the lung and pleura by enlarged mediastinal nodes, with resulting lymphedema of the pleural space, is probably the most common cause of nonchylous pleural effusion. In contrast to patients with metastatic carcinoma, pleural involvement by lymphoma is uncommonly the major factor in fluid formation. Radiation therapy to the mediastinum or to the affected hemithorax is more likely to relieve lymphomatous effusions than is intrapleural therapy or systemic chemotherapy alone.