Gut-endocrinomas (carcinoids and related endocrine variants) of the breast: an analysis of 310 reported cases.

The purpose of this study was to analyze the present status of gut-endocrinomas (carcinoids and related endocrine variants) of the breast, an extremely rare site for primary growth of such neoplasms, and to provide precise and reliable information concerning these neoplasms on varying clinicopathological aspects for investigators engaged in relevant research fields. A total of 310 cases presented in this analysis consisted of 196 carcinoids, 102 typical and 94 atypical, and 114 related endocrine variants; in the last group, the expression of "breast carcinoma with (neuro-) endocrine differentiation" was often used without referring to the term "carcinoid." A statistical evaluation was performed on most occasions based on a comparison among three groups of typical carcinoids, atypical carcinoids and related endocrine variants, or between the former two series of carcinoids and the third series of endocrine carcinomas. Statistically significant differences between the groups of carcinoids and endocrine carcinomas were recognized in terms of average age, tumor size categories of < or = 20 mm and 21-50 mm, rates of metastases, and positive neuron-specific enolase (NSE) immunohistochemistry. Contrary to our expectations no statistically significant difference between these two groups was evident in terms of overall average tumor size, Grimelius argyrophilia for endocrine nature, or postoperative 5-year survival rates in curative resection cases. It seems important to establish more precise diagnostic criteria for "endocrine carcinomas" from the viewpoint of a certain possibility that some of these neoplasms may belong to the atypical carcinoid group.