Yellow nail syndrome.

The yellow nail syndrome is characterized by yellow, slow-growing nails in association with lymphedema, idiopathic pleural effusions, chronic bronchiectasis, and chronic sinusitis. We report two patients with yellow nail syndrome in whom spontaneous clearing of the nail changes occurred without resolution of the respiratory involvement. This observation suggests that nail changes may not result from the systemic manifestations. We also report for the first time the histopathologic findings of the nail matrix and bed, which demonstrate dense, fibrous tissue replacing subungual stroma with numerous ectatic, endothelium-lined vessels that are similar to that in the pleura in yellow nail syndrome. We hypothesize that primary stromal sclerosis may lead to lymphatic obstruction, thus explaining the clinical manifestations.