Primary endocrinomas (carcinoids and variant neoplasms) of the gallbladder. A statistical evaluation of 138 reported cases.

This study was carried out to obtain extensive information on carcinoids (the carcinoid group) and related variant endocrinomas (the variant group) of the gallbladder, and to statistically analyze their characteristics from various clinicopathologic aspects. A total of 138 cases were collected from the international sources, 101 belonging to the carcinoid group and 37 to the variant group. The first group consisted of 81 cases of typical and 20 atypical carcinoids. Comparative evaluation was attempted mainly between the carcinoid and variant groups, and occasionally between the typical and atypical carcinoid series when statistical significance was suspected. The carcinoid group showed a statistically significant difference from the variant group by exhibiting a younger average age (61.7 years vs 69.7 years: P<0.01), a higher incidence of associated cholelithiasis (87.3% vs 56.0%: P<0.01), a higher incidence of small tumors 50 mm or less (85.2% vs 52.9%: P<0.01), a smaller average tumor-size (29.6 mm vs 58.7 mm: P<0.01), a lower rate of metastases (40.7% vs 70.6%: P<0.05), a higher immunoreactivity rate of chromogranin (100.0% vs 66.7%: P<0.01), a lower immunoreactivity rate of gastrin (23.8% vs 70.6%: P<0.01), and a higher five-year survival rate (60.4% vs 21.3%: P<0.0005). Significant differences in various clinicopathological aspects confirmed between the carcinoid group and the variant group suggested that endocrine carcinomas of these two groups perform a different clinical pattern, represented most clearly by postoperative outcomes. These groupings are decided on the basis of histologic patterns, namely, well to poorly differentiated endocrine carcinomas (typical to atypical carcinoids) and undifferentiated or anaplastic variants of other endocrine carcinomas. The basic criteria for such classification of these endocrine carcinomas based on international agreements are required.