E5518. A Lot to Digest: Imaging Spectrum of Duodenal Masses and Potential Complications?
  1. Jacob Owens; University of Nebraska Medical Center
  2. Elizabeth Edney; University of Nebraska Medical Center
  3. Antonia Gurney; University of Nebraska Medical Center
  4. Ryan Downey; University of Nebraska Medical Center
Small bowel malignancies are relatively rare cancers, accounting for around 2% of all gastrointestinal (GI) malignancies. When tumors do arise in this region, they tend to originate mostly from the ileum, followed by the duodenum and jejunum. Of the small bowel malignancies that do arise, the duodenum can be home to multiple different types of tumors that can have similar clinical presentations. This would include weight loss, abdominal pain or distention, GI bleeding, or even GI obstruction. Of the primary neoplasms that can arise within the duodenum, current literature focuses on four main types: adenocarcinoma (DA), lymphoma, gastrointestinal stromal tumor (GIST), and neuroendocrine tumor (NET). In this educational review, the key clinical and imaging differences between these four groups will be reviewed to help with the work-up process.

Educational Goals / Teaching Points
When reviewing the literature on primary duodenal malignancies, the main subtypes of duodenal neoplasms could overlap in their clinical syndromes as well as their appearance. However, there were certain trends discussed that could help narrow down a differential when it comes to the identification and treatment of such malignancies. Some of the key factors we want to highlight in this review include common location of these malignancies within the duodenum, associated clinical symptoms and findings, key imaging findings associated with such malignancies, and possible benign mimics that have similar presentations clinically on imaging studies.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The duodenum is a structure with complex anatomic relationships to the stomach, gall bladder, pancreas, aorta, inferior vena cava, and biliary system. Understanding duodenal anatomy and function can bolster the radiologist's ability to predict and describe complications and mimics of various duodenal pathologies. DA, the most common duodenal primary malignancy, is common in the D2 segment. This neoplasm commonly shows irregular short segment thickening or intraluminal mass with possible necrosis or ulceration. Other duodenal malignancies, such as lymphoma, can have similar imaging; a key difference is that DA is more likely to cause symptoms of bowel obstruction. Duodenal lymphoma also has varying reports on its location, differing between no predominance or D2, depending on the subtype. This also has its own characteristic "aneurysmal dilatation" appearance on imaging, but rarely has associated symptoms of obstruction. GIST is rare in the duodenum, commonly affecting D2–D4 and can take on multiple phenotypes, which makes pathology key in diagnosis. NET commonly affects D1–D2 and rarely present with classic carcinoid symptoms but have key arterial enhancement on imaging.

Overall, duodenal masses can represent a wide range of malignant and benign pathology. Knowing specific imaging characteristics can guide the radiologist to an appropriate, narrowed diagnosis and can guide staging and management.