Catch me if you can-How to make the best use of pleural effusion.

Etiology diagnosis of pleural effusion is a commonly encountered yet challenging problem. How to make the best use of pleural effusion evokes thinking. Myelomatous pleural effusion (MPE) is a rare condition and has been reported sporadically. We report an extremely rare case of multiple myeloma (MM) [IgD-lambda (λ) type, stage III B] with MPE as initial presentation and complicated with massive pericardial effusions during the progression of the disease. Cytological identification of malignant plasma cells in pleural effusion is the most direct method to diagnose MPE. What we learn from this case is that cell block can increase the sensitivity of detecting malignancies compared with conventional smear. Doctors should make best use of pleural effusion before further invasive procedure.