What are the cross sectional imaging features of GI tract adenocarcinoma?
In the stomach, focal or diffuse wall thickening, often irregular in contour and with associated luminal narrowing, or a soft tissue enhancing mass with an intraluminal polypoid or plaquelike component is seen, sometimes with areas of ulceration, necrosis, or calcification. Direct spread of tumor into the perigastric fat or into other surrounding organs (e.g., distal esophagus, duodenum, transverse colon, liver, spleen, or pancreas) may also occur. In more advanced stages of disease, regional lymphadenopathy, distant metastatic disease (most commonly involving the lungs, liver, osseous structures, and adrenal glands), or direct spread to the peritoneal cavity may be encountered.
In the small bowel, adenocarcinoma is uncommon but most commonly occurs in the duodenum or proximal jejunum and occurs with increased frequency in the distal ileum in the setting of Crohn’s disease. Focal small bowel wall thickening (often asymmetric or lobulated in contour) or an annular mass with luminal narrowing is typically seen, often with associated bowel obstruction. Direct spread into the peritoneal cavity, regional lymphadenopathy, and distant metastatic disease may also be present.