Gallbladder metastases are rare and usually represent an advanced and end-stage of malignancy. Malignant melanoma and gastric carcinoma account for the most common primary malignancies to seed metastases to the gallbladder, in Western and Asian societies, respectively.
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Epidemiology
They represent <5% of all gallbladder cancers 1.
Clinical presentation
Most patients with gallbladder metastases are asymptomatic, and the metastases are detected on surveillance or staging imaging.
Acute cholecystitis is the most common symptomatic presentation of gallbladder metastases, so right upper quadrant pain and a positive Murphy's sign may be present 2. Jaundice is also common. Liver function test derangement and raised inflammatory markers (e.g. CRP) may also be found 2.
Pathology
The most common primary malignancy in Western society metastasizing to the gallbladder is malignant melanoma, which represents 50-67% of cases 3,8. In Asian society, the most common is gastric cancer 1,8.
Other malignancies metastasizing to the gallbladder include lung cancer, renal cell carcinoma 4, hepatocellular carcinoma 6, and non-Hodgkin lymphoma 7. Most commonly the metastases are caused by hematogenous spread, this produces serosal tumor deposits in the gallbladder, which develop into rapidly growing polypoid masses often with areas of internal hemorrhage 4. In one study it was diagnosed synchronously in one-third of cases and metachronously in two-thirds of patients 4.
Radiographic features
Ultrasound
One or more hyperechoic masses, usually larger than 1 cm in diameter, with a broad base and minimal acoustic shadowing. In cases of concurrent acute cholecystitis, mural thickening may be seen. Doppler may show abnormal flow within the lesion 4.
CT
One or more enhancing polypoid masses within the gallbladder, often with associated mural thickening 4. The enhancement varies:
hypervascular lesions with arterial enhancement and early washout are likely related to melanoma, HCC, or RCC as a primary 8
portal venous persistent enhancement is more commonly seen in metastases from gastrointestinal tract adenocarcinomas 8
MRI
T1: often hyperintense when related to melanin or hemorrhagic content (e.g. melanoma and RCC as primaries) 4
T2: hypointense 4
However, in the presence of internal hemorrhage, the signal may be heterogeneous and be different from that described above 5.
Treatment and prognosis
Although the primary malignancy is often advanced at the time when gallbladder metastases are diagnosed, cholecystectomy may offer a survival benefit 4.
Complications
biliary fistula formation
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