Malignant melanoma of the gallbladder

A 75 year woman developed a primary malignant melanoma of the gallbladder. The patient presented with abdominal pain in the upper right quadrant typically seen in acute cholecystitis. Neither intravesical concretions nor cholestasis was seen. Ultrasound demonstrated hyperechogenic intraluminal ''school of fish'' reflections, which are typical for metastatic melanoma to the gallbladder. Intravesical fluid collection was not present. The tumor did not expand past the wall of the gallbladder. The main sonographic features are hyperdense intraluminal strands of tumor and the lack of fluid. Computed tomography showed solid intraluminal masses with hypodensive and partially hyperdensive reticular structure.