CT: Usually polyploid enhancing nodule or mass within GB lumen, but may appear as focal mural thickening
MR: Melanoma classically hyperintense on T1WI and hypointense on T2WI
US: Immobile polypoid mass (usually > 1.5 cm) ± adjacent GB wall thickening
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Melanoma classically described as hyperechoic, without acoustic shadowing
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May be single or multiple
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Flow characteristics variable on color Doppler, but usually evidence of internal flow
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Lymphoma of GB
High-grade lymphomas often present as bulky mass (usually hypodense and homogeneous), while low-grade lymphomas cause only mild wall thickening
Usually other evidence of lymphoma elsewhere, including adenopathy and splenomegaly
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Metastatic disease to biliary tree
Indistinguishable from cholangiocarcinoma, including bile duct wall thickening, discrete soft tissue mass in porta hepatis, and proximal biliary dilatation/obstruction
PATHOLOGY
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Metastases to GB are rare, representing < 5% of all GB malignancies
Melanoma accounts for 50-67% of GB metastases, with lung and renal malignancies also common
Most patients with GB metastases have end-stage disease with widespread metastatic disease
May rarely cause cholecystitis (due to cystic duct obstruction) or jaundice
Related
Diagnostic Imaging_ Gastrointes - Michael P Federle
