Clinicopathological Study of Mass-forming Gallbladder Cancer Focusing on the Grade of Cellular Dysplasia

The relationship between the clinicopathological features and the grade of cellular dysplasia of the neoplastic glands in mass-forming gallbladder cancer was investigated. In this retrospective study, 41 mass-forming （≧1cm） gallbladder cancer specimens from 83 resected cases were examined. Tumors were classified into three groups: Group A had intraluminal masses consisting of neoplastic glands with only low-grade dysplasia; Group B had mixed low- and high-grade dysplasia, and Group C had only high-grade dysplasia. Of the 41 tumors, 13 were classified as Group A, 11 as Group B, and 17 as Group C. For Group A, B, and C, respectively, the mean tumor diameter was 1.6, 3.7 and 3.4cm; macroscopic type （pedunculated/semi-pedunculated/sessile） was 7/5/1, 4/6/1 and 0/10/7; frequency of an invasive component inside the mass was 0％, 9％ and 82％; and cell lineage （biliary/metaplastic/mixed） was 2/1/10, 8/1/2 and 14/1/2. In addition, invasion depth （Tis＋T1/T2/T3） was 13/0/0, 7/4/0 and 3/10/4; lymph node metastases were present in 0％, 9％ and 24％ of patients; 3-year survival rate was 100％, 100％ and 82％; and 5-year survival rate was 100％, 100％ and 69％, for A, B and C, respectively. Significant intergroup differences were seen for positive lymph node metastasis rate and 5-year survival rate. The present study indicates that the clinicopathological features of mass-forming gallbladder cancer are different depending on the grade of cellular dysplasia of the mass lesion. The tumors in Groups A and B were of lower malignancy than those in Group C and the prognosis of patients in the former groups was excellent. Group A and B tumors may be intracholecystic papillary-tubular neoplasms, a recently proposed new disease concept.