Version July 2025
| Grade | Tubular or clustered growth (low-grade pattern)*¶ | Loss of tubular or clustered growth (any combination of high-grade patterns)¶Δ |
| 1 | >75% | <25% |
| 2 | 50 to 75% | 25 to 50% |
| 3 | <50% | >50% |
GCA: goblet cell adenocarcinoma; WHO: World Health Organization.
* Histologic low-grade patterns include tubules composed of goblet-like mucinous cells, variable numbers of endocrine cells, and Paneth-like cells with granular eosinophilic cytoplasm. Some tumor cell clusters lack lumina and appear as small groups of cohesive goblet-like cells. Mild architectural disarray or tubular fusion can be seen. Nuclear atypia is mild, and mitoses are infrequent. Extracellular mucin is often present and sometimes abundant.
¶ Perineural invasion is common among all grades and is not prognostically significant. Lymphovascular invasion is more common in high-grade GCA.
Δ Histologic high-grade patterns include tumor cells infiltrating as single mucinous or nonmucinous cells, complex anastomosing tubules, cribriform masses, sheets of tumor cells, and large aggregates of goblet-like or signet-ring-like cells. In some cases, conventional adenocarcinoma may be seen with irregular glands lined by columnar cells with malignant-appearing nuclei. Desmoplastic stromal response, high-grade cytological features, numerous mitoses with atypical mitotic figures, and necrosis may be present in high-grade areas.