| Morphologic criteria |
Typical GCC (group A) | Well-defined goblet cells arranged in clusters or a cohesive linear pattern |
Minimal cytologic atypia |
Minimal to no desmoplasia |
Minimal architectural distortion of the appendiceal wall |
Degenerative change with extracellular mucin is acceptable |
Adenocarcinoma ex GCC, signet ring cell type (group B) | Goblet cells or signet ring cells arranged in irregular large clusters, but a lack of confluent sheets of cells |
Discohesive single-file or single-cell infiltrating pattern |
Significant cytologic atypia |
Desmoplasia and associated destruction of the appendiceal wall |
Adenocarcinoma ex GCC, poorly differentiated carcinoma type (group C) | At least focal evidence of goblet cell morphology |
A component (>1 low-power field or 1 mm2) not otherwise distinguishable from a poorly differentiated adenocarcinoma, which may appear as either (a) gland forming, (b) confluent sheets of signet ring cells, or (c) undifferentiated carcinoma |