Incidental duodenal and pancreatic tail lipomas: imaging features and clinical implications

Background
Lipomas are benign mesenchymal tumors of mature adipose tissue, rarely occurring in the gastrointestinal tract or pancreas. Duodenal lipomas comprise ~4% of gastrointestinal lipomas, typically arising in the second duodenal portion, with peak incidence in the fifth to seventh decades. Most are asymptomatic and discovered incidentally during endoscopy or imaging, though symptomatic cases can present with bleeding, obstruction, or pain. Pancreatic lipomas are even rarer (~0.012% in cross-sectional imaging), stable in size, and lack malignant potential.
These lesions exhibit characteristic fat attenuation on CT (-90 to -120 Hounsfield units), distinguishing them from liposarcomas or focal fatty infiltration. Incidental findings underscore advanced imaging's diagnostic value, with conservative management standard unless symptoms develop. This report describes two incidental cases: a duodenal lipoma and a pancreatic tail lipoma, focusing on radiographic features and implications.
Methods
Two unrelated patients underwent imaging for different indications. Case 1: a 62-year-old man with dyspepsia evaluated by upper endoscopy, endoscopic ultrasound (EUS), and contrast-enhanced CT. Case 2: a 68-year-old woman on surveillance CT for a prior renal cyst, followed by MRI. Both used multi-slice CT with densitometry; MRI confirmed findings. Histopathology was deferred due to benign imaging. Follow-up imaging was planned at 6 and 12 months. Diagnostic criteria included homogeneous hyperechoic submucosal masses on EUS (duodenal) and non-enhancing fat-density nodules on CT/MRI (pancreatic).
Results
Case 1 revealed a 2.5 cm submucosal bulge in the duodenal bulb. EUS showed a homogeneous hyperechoic lesion from the submucosa; CT confirmed -105 HU fat attenuation without invasion or obstruction. The patient was asymptomatic, with no change at 12-month follow-up.
Case 2 identified a 1.8 cm well-circumscribed, lobulated mass in the pancreatic tail (-110 HU), without solid components or ductal dilatation. MRI showed fat signal on T1 (suppressed on fat-saturated sequences). The lesion remained stable, with no enzyme elevation or symptoms.
Conclusions
Incidental duodenal and pancreatic lipomas are benign and warrant conservative management. Characteristic non-invasive imaging prevents misdiagnosis as malignancy and avoids unnecessary interventions. Stability on short-term follow-up supports watchful waiting over resection in asymptomatic patients. These cases reinforce the benign natural history of such lipomas and the value of multidisciplinary evaluation for optimal outcomes.