Endoscopic ultrasonography (EUS) is an established diagnostic and therapeutic modality in gastroenterology. Although most gastroenterologists are not trained in the practice of EUS, it is important that they understand the principles of the technique and the indications for EUS in order to offer optimal patient care.

This chapter provides case vignettes with selected images that illustrate common diagnostic and therapeutic indications for EUS. A brief overview of the role of EUS in such indications is included. As a complete representation of images encountered in endosonography could not be provided here, the authors recommend that anyone interested in learning EUS should review textbooks dedicated to the practice of EUS and seek out an established EUS training program.

Types of echoendoscopes

There are two major types of echoendoscopes: radial imaging and linear imaging. Radial echoendoscopes provide good cross‐sectional anatomical imaging, while linear echoendoscopes transmit ultrasound waves in the same axis as the long shaft of the transducer, which allows for real‐time therapeutic intervention, most commonly fine‐needle aspiration (Figure 88.1). Figures 88.2–88.6 depict selected images of normal histology or anatomy as visualized by EUS.

Case examples showing the use of EUS follow.

Case 1

A 57‐year‐old man with a history of reflux presents with 2 months of progressive dysphagia for solids more than liquids. He reports a 15 lb weight loss. A computed tomography (CT) scan of the thorax reveals thickening of the distal esophagus. Upper endoscopy reveals a lesion in the distal esophagus (Figure 88.7a). The EUS (Figure 88.7b) shows a hypoechoic lesion which extends into the muscularis propria (T2). Multiple round, hypoechoic lymph nodes measuring >1 cm are seen proximal to the tumor (Figure 88.7c). These EUS features are very suggestive of malignant involvement. EUS stages the tumor as T2N1Mx.

Case 2

A 43‐year‐old man with a history of cystic fibrosis presents with hemoccult‐positive stools and mild anemia. Upper endoscopy reveals a polypoid mass in the distal esophagus (Figure 88.8a). Biopsy confirms adenocarcinoma. EUS shows an asymmetrical, hypoechoic mass with submucosal invasion (Figure 88.8b). Endoscopic mucosal resection is performed as ablative therapy (Figure 88.8c).

Case 3

A 65‐year‐old woman with weight loss undergoes CT of the abdomen. The CT scan shows tumor in the right lung and a left adrenal mass. Linear EUS demonstrates a mass in the left adrenal (Figure 88.9a). The results of a fine needle aspiration confirm the diagnosis of stage IV nonsmall cell lung cancer (Figure 88.9b).

Case 4

A 47‐year‐old man with a history of gastroesophageal reflux undergoes upper endoscopy. A submucosal mass of about 2 cm is identified (Figure 88.10a). Linear EUS demonstrates a well‐circumscribed, hypoechoic mass originating from the muscularis propria layer or fourth layer of the stomach wall (Figure 88.10b). Fine‐needle biopsy demonstrates spindle‐shaped cells that stain positive for C‐kit protein. A gastrointestinal stromal cell tumor (GIST) is diagnosed.

Case 5

A 57‐year‐old man undergoes upper endoscopy for epigastric pain and 5 lb weight loss. A gastric ulcer is identified and endoscopic biopsy confirms adenocarcinoma. EUS reveals a tumor that extends through the muscularis propria and into the subserosal connective tissue (T3) (Figure 88.11a). Round, hypoechoic lymph nodes measuring >1 cm adjacent to the tumor are very suggestive of malignant lymph nodes (N1) (Figure 88.11b).

Case 6

A 68‐year‐old man presents with epigastric pain, weight loss, and new‐onset diabetes. A CT scan shows a pancreatic body mass. Linear EUS shows a hypoechoic mass involving the splenic artery (Figure 88.12), which is confirmed to be adenocarcinoma by EUS‐guided fine‐needle aspiration.

Case 7

A 49‐year‐old woman suffers from episodes of hypoglycemia. Prior imaging studies failed to identify a clinically suspected insulinoma. EUS reveals a 5 mm well‐circumscribed hypoechoic lesion in the pancreatic tail (Figure 88.13). Distal pancreatectomy is performed and the symptoms resolve.

Case 8

An asymptomatic 65‐year‐old woman has a incidental finding of a 2 cm pancreatic cyst. MRCP shows a multiloculated cyst in the tail of the pancreas. EUS reveals a lesion that is well‐circumscribed with a microcystic appearance, which is classic for a serous cystic neoplasm. nCLE is perfomed and reveals a superficial vascular network which is pathognomonic for a serous cystic neoplasm (Figure 88.14).