Sometimes, despite the use of all the above-mentioned modalities, the diagnosis is not clear. In such cases, Thoracoscopy i.e. visualisation of inside of the chest cavity by a telescope inserted through a 5-10mm opening can be of immense help. This can be performed under local or general anaesthesia and allows detailed visualisation of inside of the chest with an opportunity to take biopsy from any abnormal looking area, under vision. Most of the undiagnosed cases get diagnosed by this procedure. In the current practice, it is rarity to need to open a patient’s chest(thoracotomy) just to take tissue for diagnosis.