Inclusion Criteria:  Candidate for diagnostic thoracentesis. The General Data Protection Regulation (Regulation (EU) 2016/679 of the European Parliament and of the Council of 27 April 2016) and the Law on Personal Genetic Information and Health Information (Decree-Law no. 131/2014) is fulfilled. Participation in the Study is completely voluntary. It is possible to drop out of the study at any time without affecting the quality of medical care. The information obtained from this study may originate scientific publications, without jeopardizing the anonymity of the Participants. During the course of the Study, it is possible to ask the investigators questions that you consider convenient. This study does not impose any cost on the participants.  Exclusion Criteria:  Participants with unstable / severe medical illness (per investigator's judgment), coagulopathies and / or bleeding disorders, immunodeficiency syndromes (primary or acquired - including HIV infection), active and untreated HCV infection, HBV and active history of intravenous drug addictions.