{"type":"rich","version":"1.0","provider_name":"Transistor","provider_url":"https://transistor.fm","author_name":"Board Pearls","title":"Chapter 28, Ep 7 of 7: EUS Beyond the Ducts","html":"","width":"100%","height":180,"duration":889,"description":"The final episode turns EUS from a guide for therapy into a diagnostician and a palliator, and it runs on one habit: reason from substrate to answer. The five alternating wall layers plus echotexture place a subepithelial lesion and narrow the differential before a needle moves, so a hypoechoic layer-four mass is a GIST until tissue proves otherwise. The needle choice then turns on a single distinction, cells versus architecture, because lymphoma, GIST, and autoimmune pancreatitis all live in structure a core preserves and cytology destroys. Finally the same probe that finds the tumor treats its pain: alcohol neurolysis for cancer, a reversible steroid block for benign disease, with complications that read straight off the interrupted sympathetic outflow.\n \nTopics covered\n\nThe five EUS gut-wall layers\nLayer-four GIST versus leiomyoma\nSize threshold for sampling muscularis lesions\nOther layers by echotexture\nFine needle aspiration versus biopsy\nRapid on-site evaluation and cyst fluid\nCeliac plexus neurolysis for cancer pain\nNeurolysis versus reversible block in benign disease\nComplications from interrupted sympathetic outflow\n \n \nKey decisions\n\nPlace a subepithelial lesion by its wall layer and echotexture: a hypoechoic homogeneous mass arising from layer four, the muscularis propria, is a GIST until proven otherwise.\nDo not call a layer-four hypoechoic mass a leiomyoma on imaging, because GIST (CD117 and DOG1 positive) and leiomyoma (desmin and smooth muscle actin positive) are indistinguishable sonographically and separate only on immunohistochemistry.\nObtain tissue for any muscularis-propria lesion two centimeters or larger, since within layer four increasing size correlates with malignant behavior.\nChoose the needle by whether the diagnosis lives in cells or architecture: cytology suffices for pancreatic adenocarcinoma, but lymphoma, GIST, and autoimmune pancreatitis need a fine needle biopsy core, which also largely obviates rapid on-site evaluation.\nRead...","thumbnail_url":"https://img.transistorcdn.com/-FuAdDBcPDLhEoUmroZKtOBRvuBn_FHPpYlh41hOnU4/rs:fill:0:0:1/w:400/h:400/q:60/mb:500000/aHR0cHM6Ly9pbWct/dXBsb2FkLXByb2R1/Y3Rpb24udHJhbnNp/c3Rvci5mbS9iNzlh/ZTU4Y2MzNWExMjQ5/MjA5OWMwMmI3ZTk5/NGFiZS5wbmc.webp","thumbnail_width":300,"thumbnail_height":300}