The descending duodenum is a structure with distinct
pathologic processes and anatomic relationships that requires a systematic approach to the differential diagnosis. Because of its tubular shape and fixed position in the retroperitoneum, both intrinsic duodenal and juxtaduodenal diseases are capable of producing
luminal narrowing and obstruction. Duodenal lesions may be located in the mucosa or submucosa. Extraduodenal lesions may originate in adjacent structures--such as the pancreas, liver, gallbladder, colon, and lymph nodes--or from other retroperitoneal structures. Causes of
duodenal obstruction include intraluminal masses, such as
bezoars; duodenal
inflammation, such as as
peptic ulcers and
Crohn disease;
hematomas; and benign or malignant mucosal and intramural
tumors. Pancreatic
inflammation;
tumors; and extrinsic compression caused by gallbladder processes, hepatic masses, retroperitoneal fluid collections, and
tumors, including
lymphoma, may produce
duodenal obstruction. Abdominal radiography,
barium studies, multidetector computed tomography, magnetic resonance imaging, and positron emission tomography may be used to depict and characterize duodenal
strictures. Integration of imaging, clinical, laboratory, and endoscopic findings plays a major role in establishing a diagnosis of obstructive duodenal
strictures.