A study of appendiceal crypt cell adenocarcinoma (so-called goblet cell carcinoid and its related adenocarcinoma)

Goblet cell carcinoids (GCCs) of the appendix are rare tumors, characterized by a carcinoid-like organoid growth pattern. Despite the term carcinoid, neuroendocrine features are inconspicuous, and its behavior is distinct from carcinoid. Its high-grade counterpart is designated as adenocarcinoma ex GCC. We conducted a retrospective study of 105 tumors to find prognostic values of a variety of clinicopathologic features. The tumors were subclassified as low grade, equivalent to classic type, and high grade, defined as loss of organoid pattern, and a proportion (%) of low and high grades were documented in each tumor. Correlations between survival and various clinicopathologic parameters were investigated. One-third were pure low grade, while the remainder contained variable high-grade component ranging from 5% to 95%. Neuroendocrine cell component ranged from 0% to 90% (median, 5), while mucus cell component ranged from 5% to 100% (median, 70). By univariate analysis, size, stage, high-grade component, nuclear grade, surgery, and chemotherapy correlated with cancer-related survival (CSS), and by multivariate analysis, stage (P=.001), high-grade component (P=.008), and tumor size (P=.005) correlated with CSS. There was significant difference in CSS when the cases were grouped by high-grade component: <40%, 40% to 90%, and ≤90% (P<.001). Our results indicate that staging and proportion of high-grade histology may provide important prognostic information. Neuroendocrine component was insignificant in both low- and high-grade areas. In light of our findings, this tumor type is best regarded as a variant of adenocarcinoma, and the term crypt cell adenocarcinoma more appropriately reflects the nature and origin of this tumor group.