Pancreatic lipomas are uncommon mesenchymal tumors of the pancreas.

Clinical presentation

Rarely symptomatic, they are most often detected incidentally on cross-sectional imaging for another purpose. If they do cause symptoms, it will typically be those related to regional mass effect from the mass.

Pathology

Pancreatic lipomas are composed of mature fat cells with thin internal fibrous septa. They differ from pancreatic lipomatosis in that they have well-defined margins covered by a thin collagen capsule.

Radiographic features

Correct diagnosis is important to avoid confusion with a neoplastic process. Most contain macroscopic fat.

Ultrasound

• difficult to diagnose: may be hyperechoic or hypoechoic

CT

• well-circumscribed, lobulated lesion in the pancreas

• generally fat attenuation (≤ -30 HU)

• non-enhancing

MRI

• well-circumscribed, lobulated lesion in the pancreas

• T1 and T2 hyperintense

• saturates on a fat-saturated sequence

• may not be hypointense on an out-of-phase sequence (edge may show "india-ink" artifact)

Treatment and prognosis

They are benign lesions, and only rarely require resection.

Differential diagnosis

• pancreatic mature cystic teratoma (dermoid): even more rare; may have associated calcifications

• liposarcoma: should be considered if there are atypical findings such as an infiltrative lesion, a large lesion, or solid enhancing elements

• focal fatty infiltration: there is overall decrease in pancreatic volume with preserved lobular contour and replacement of the pancreatic parenchyma by fat density ³

• pseudohypertrophic lipomatosis: enlarged pancreatic size with fat density ⁴