Immunohistochemistry of pleural tissue showed that majority of tumour cells were positive for synaptophysin and a few cells were positive for Ki-67 (2%) and negative for pan-cytokeratin, calretinin, Wilm's tumour protein 1 (WT1), desmin, vimentin, carcinoembryonic antigen (CEA), thyroid transcription factor 1 (TTF1), and CD 56 (Figure 4). Here, CEACAM5 is linked to neoplasm.