Clinicopathological features and immunoexpression profiles of goblet cell carcinoid and typical carcinoid of the appendix.

Goblet cell carcinoid (GCC) of the appendix is currently classified as a neuroendocrine tumor, together with typical carcinoid (TC) of the appendix. However, whether GCC is a variant of TC or a mucin-producing adenocarcinoma is still controversial. To get a better understanding, we investigated the clinicopathological features of 55 Chinese patients (26 GCCs and 29 TCs), and explored the histochemical properties and expression profiles of CK7, CK20, P63, CEA, CgA, NSE, CD56, and Ki67 in 37 out of these 55 patients (18 GCCs and 19 TCs). Our results showed GCC had a male predominance, older age involvement, significantly larger tumor size, and significantly more frequency of mesoappendix infiltration than TC. Alcian blue/PAS stains were positive in all the GCC cases, while negative in all the TC cases. CK7 and CK20 expressions were significantly more frequent in GCC (P = 0.03 and 0.00001, respectively). However, P63 expression was detected in none of the GCC cases but in 6 TC cases (P = 0.02). Although the expression of CgA was similar, strong expression (3+) was significantly more frequent in TC (P = 5.7 × 10(-11)). Also, NSE and CD56 expressions were significantly more frequent in TC (P = 0.02 and 1.26 × 10(-4), respectively). CEA expression was significantly more frequent in GCC (P = 2.4 × 10(-6)). Finally, Ki67 index was low in GCC (4.7%), but significantly higher than TC (0.9%) (P = 5.4 × 10(-6)). Taken together, these distinct features support that GCC differs from TC, a classical neuroendocrine tumor, and harbors an immunophenotype of adenocarcinoma. Therefore, the term "low grade adenocarcinoma with neuroendocrine differentiation" might be more appropriate for GCC.