Investigation of the BRAF mutation status in the pleural punctate in patients with malignant melanoma, colorectal or lung cancer, that show a BRAF mutation in the primary tumor and the comparison of the result with the conventional cytological / immunohistochemical and molecular cytology findings of the pleural punctate

Interventions: Group 1: As part of the study, the therapeutically extracted pleural effusion will be examined once by using the fully automatic diagnostic system Idylla from BIOCARTIS.
The aim is to examine whether the gene mutation BRAF-V600 is detectable in the pleural puncture, even if no malignant cancer cells could be found. Since the cancer gene has already been detected with the NGS procedure on primary tumor or a metastasis, a direct comparison of both methods (NGS procedure and BIOCARTIS procedure) should be carried out in order to obtain a possible temporal benefit over the current investigations on the primary tumor or the metastasis.
Primary outcome(s): Investigation of the possibility to increase the sensitivity of diagnoses of malignant pleural effusion compared to conventional pleural cytology by using the Idylla ctBRAF mutation assay
Study Design: Allocation: ; Masking: ; Control: ; Assignment: ; Study design purpose: diagnostic