We herein report an extremely rare adult case presenting with life-threatening pulmonary lymphedema secondary to generalized lymphedema. A 47-year-old woman with generalized lymphedema from her feet to below her chest, had undergone surgical ligation of the thoracic duct and bilateral pleurodesis for the treatment of intractable idiopathic chylothorax three years earlier. Chest computed tomography demonstrated bilateral ground-glass opacities, air-space consolidation and interlobular septal wall thickening, presenting as a crazy-paving appearance predominantly on the gravity side. Bronchoalveolar lavage revealed marked lymphocytosis. She was treated with long-term oxygen therapy with noninvasive positive-pressure ventilation, followed by lymphovenous anastomoses of the lower extremities.