2. ClassificationAccording selleck kinase inhibitor to Tang et al., GCC can be classified as typical GCC (Group A) and adenocarcinoma ex-GCC on the basis of the histologic features at the primary site of the tumor. The adenocarcinoma ex-GCC group can be further divided into signet ring cell type (Group B) and poorly differentiated adenocarcinoma type (Group C). The classification is based only on morphologic features at the primary site, that is, the appendix. Group A has well-defined goblet cells arranged in clusters or cohesive linear pattern, minimal cytologic atypia, minimal to no desmoplasia, minimal architectural distortion of the appendiceal wall, and degenerative change with extracellular mucin is acceptable.

Group B has goblet cells or signet ring cells arranged in irregular large clusters, but lack of confluent sheets of cells, discohesive single file, or single cell infiltrating pattern, significant cytologic atypia, and desmoplasia and associated destruction of the appendiceal wall. Group C has at least focal evidence of goblet cell morphology, a component (>1 low power field or 1mm2) not otherwise distinguishable from poorly differentiated adenocarcinoma, which may appear as either (a) gland forming, (b) confluent sheets or signet ring cells, or (c) undifferentiated carcinoma [12].A recent study by Jiang et al. from 2012 shows a possible connection between GCC and schistosomiasis, which is the only potential risk factor for GCC identified to date [13]. They examined appendix samples from 3 patients with combined GCC and appendiceal schistosomiasis, 6 patients with GCC only, 12 patients with appendiceal schistosomiasis only, and 12 cases with normal appendix.

In this study, their findings suggest that appendiceal schistosomiasis is associated with both increased proliferation and neuroendocrine differentiation of mucosal pluripotent crypt cells, and that it hereby may contribute to development of GCC [13]. However, these data needs to be confirmed by other research groups.3. EpidemiologyGoblet cell carcinoids are considered a distinct entity of appendiceal tumors and occur in 0.3%�C0.9% of appendectomies where they comprise 35%�C58% of all appendiceal neoplasm [4, 14, 15], and less than 14% of all malignant GSK-3 tumors of the appendix [16]. Thus GCCs are extremely rare and in the period 1973�C2001 with an incidence of approximately 0.05/100,000 per year compared to appendiceal endocrine tumors with an incidence of 0.63/1,000,000 per year in the SEER database.They are most often seen in patients in their fifties or sixties with a second peak in the seventies [2, 16, 17], but McCusker et el.