<prompt> To differentiate malignancy from benign lesion in GIT, investigation of choice:USGBiopsyEndoscopyP.E.T scan  <response>: Ans. b BiopsyRef: Chapter 91: Harrison 18th ed. Taking multiple biopsies increases the yield. Cytologic examination of tumor brushings complements standard biopsies and should be performed routinely. The extent of tumor spread to the mediastinum and para-aortic lymph nodes should be assessed by CT scans of the chest and abdomen and by endoscopic ultrasound. Positron emission tomography scanning provides a useful assessment of resectability, offering accurate information regarding spread to mediastinal lymph nodes 