Chyliform (pseudochylous) pleural effusion.

A chyliform (pseudochylous) effusion is an uncommon disease entity which develops after an exudative effusion is in situ for a long time. It is commonly initiated by a tuberculous pleurisy and it is important to exclude the presence of active tuberculosis. We present a case with the characteristic features. Chylothorax was excluded by demonstrating in the pleural fluid a relatively low level of triglycerides with a cholesterol/triglyceride level of less than one and abundant cholesterol crystals.