The yellow nail syndrome. Light and electron microscopic aspects of the pleura.

The yellow nail syndrome is a rare cause of recurrent pleural effusions. We studied a case of this entity, placing special emphasis on the microscopic and ultrastructural aspects of the pleural lymphatics. The patient had the classic symptoms of recurrent bilateral pleural effusions, yellow, dystrophic fingernails and toenails, and lower-limb edema. To control the pleural effusions, a left parietal pleurectomy was performed. Histologic study showed both pleura to be thickened with fibrosis and chronic inflammatory infiltration. The lymphatic capillaries in the visceral pleura were dilated. Electron microscopy confirmed the lymphatic nature of these capillaries. We believe that these ectatic lymphatic capillaries suggest a downstream obstruction to the lymph drainage.