T1b (MP) carcinoma of the gallbladder showing a thickened outermost hyperechoic layer

Abstract

Patients with an early gallbladder carcinoma, confined to mucosa or muscle layer, are candidates for a laparoscopic cholecystectomy because they seldom have lymph node involvements. Hence, a differential diagnosis of gallbladder tumors is essential with invasion depth of carcinoma. A symptomless 64-year-old man was referred to the hospital with a growing gallbladder tumor, showing no elevation of serum carcinoembryonic antigen or carbohydrate antigen 19-9. Ultrasound showed a heterogeneous hyperechoic gallbladder tumor, 3cm in diameter, with microcysts plus comet-like echoes and thickened outermost hyperechoic layer beneath the lesion without a deep hypoechoic area. Precontrast abdominal CT depicted the lesion, diffusion weighted imaging of MR revealed its decreased diffusion and endoscopic ultrasound showed an anomalous arrangement of the pancreatobiliary ducts. An early gallbladder carcinoma was suspected from the ultrasound findings. Laparoscopic cholecystectomy with liver bed fatty tissue extirpation was then performed. Macroscopically, an elevated lesion, 32×29mm in size, was evident in the resected gallbladder. Histologically, a tubular adenocarcinoma (tub1-tub2) confined to muscle layer was demonstrated. The subserosal adipose layer beneath the lesion was thickened and free from carcinoma consistent with the ultrasound image. A T1b gallbladder carcinoma could show a thickened outermost hyperechoic layer.