Conventionally, pseudochylothorax is viewed as a single disease entity; this preconception should be challenged. The majority (54%) of the published cases of pseudochylothorax were associated with TB, followed by rheumatoid arthritis (9%).2 A large number of other conditions has also been implied, although each has been linked with very few cases of pseudochylothorax. Pseudochyle is defined by a high pleural fluid cholesterol composition (presence of cholesterol crystals on microscopic examination or cholesterol concentration > 200 mg/dL).3 This definition makes no assumption about the underlying pathogenetic mechanisms leading to pseudochyle formation. The previous literature has always associated pseudochylothorax with significant pleural thickening (a complication relatively common in TB) and assumed the fibrotic pleura plays a role in the accumulation of cholesterol within the pleural cavity. Our report of six cases of pseudochylothoraces—all associated with arthritis—without significantly thickened pleura contradicts such belief. Rather than one unifying mechanism resulting in pseudochyle formation, it is possible that pseudochyle actually represents a common end point of a variety of disease pathophysiologic conditions; those associated with TB may arise from a separate mechanism from those associated with arthritis. Expansion of such a theory could provide a plausible explanation for the diversity in rates of formation of pseudochyle and other pathologic findings (such as degree of pleural thickening), as seen in our series.