GOBLET CELL CARCINOID
This is a malignant tumor infiltrating the cecal mesentery showing nests, glands and files of discohesive signet ring cells infiltrating a desmplastic stroma. Immunohistochemistry is positive for CDX2 (not shown in pictures), TTF1, CK20, Villin and mild positivity for Synaptophysin. The immunostains are negative for CK7 and chromogranin.
With the relatively bland architectural pattern, not very pleomorphic goblet cells, perineural extension and immunostains showing positivity for TTF1, CK20+, Villin+ and CK7 negative, I think the most probably diagnosis is a goblet cell adenocarcinoid or a signet ring type of Adenocarcinoma ex goblet cell carcinoid.
Goblet Cell Carcinoid, also called mucinous carcinoid, adenocarcinoid or microglandular goblet cell Carcinoma is a different tumor to signet ring Ca of the appendix and shows differentiation between typical Carcinoid and Adenocarcinoma. The 5 year survival of this tumor is around 75%. A percentage disemminate to peritoneum or liver. The prognosis is considered intermediate between signet ring Carcinoma and Classical Carcinoid.