Contrast Enhanced Ultrasound of a Gallbladder Lesion in a Patient with a History of Renal Cell and Rectal Cancer

The gallbladder is an uncommon site of metastatic cancer. Although ultrasound can be regarded as a first line investigation for the detection of gallbladder lesions, differentiation between benign and malignant tumors usually requires resection. Real-time contrast enhanced ultrasound (CEUS) is a well-established technique for the classification of liver, pancreatic, and renal diseases (Weskott, 2008). The application of CEUS in the diagnosis of gallbladder tumors has rarely been described. We report the application of contrast enhanced ultrasound for the characterization of a gallbladder lesion in a 63-year-old patient with a history of renal cell and rectal cancer. 1. Introduction Polypoid lesions of the gallbladder are frequently found during abdominal ultrasound. The majority of these lesions represent benign cholesterol polyps and are less than 10？mm in size [1]. Primary adenocarcinoma of the gallbladder is an uncommon malignancy. Metastatic cancer to the gallbladder is also a rare finding occurring most often in melanoma, gastric cancer, and renal cell carcinoma [2]. Preoperative differentiation between benign and malignant gallbladder tumors is often difficult. This paper describes a case of a gallbladder lesion in a patient with a history of rectal and renal cell carcinoma. 2. Case Report A 63-year-old Caucasian man was admitted to our hospital for further workup of a solitary pulmonary lesion. A simultaneous diagnosis of stage I renal cell carcinoma of the left kidney and adenocarcinoma of the rectum had been made in March 2005 which was treated by left nephrectomy, total mesorectal resection, and adjuvant radiochemotherapy according to the AIO protocol. Postoperative tumor staging and grading of the rectal carcinoma was pT3, pN0 (0/15), G2, R0, and M0. Regular followup until July 2010 was without pathological findings and the carcinoembryonic antigen (CEA) and CA19-9 serum concentrations were normal. A computed-tomography-guided core biopsy of the pulmonary lesion was performed; histological and immunohistochemical analysis showed an adenocarcinoma consistent with metastatic colon cancer. On further workup, an abdominal ultrasound showed a 25？mm polypoid lesion within the gallbladder (Figure 1). Contrast enhanced ultrasound was performed for further characterization. Imaging in low mechanical index (MI) technique after intravenous injection of 5？mL sulphur hexafluoride microbubbles (SonoVue) showed an intense homogenous contrast signal within the gallbladder mass. Contrast enhancement was detected after 20 seconds and preceded the appearance of