Case 3

A 60-year-old female presented with nonspecific abdominal pain at right lower quadrant and she underwent appendectomy.

1. What's the diagnosis?

A: Appendicitis

B: Carcinoid

C: Mucinous adenocarcinoma

D: Goblet cell adenocarcinoma

E: Appendix with mucinous metaplasia

Answer

The correct answer is D. This case represents a low-grade goblet cell adenocarcinoma and the essential feature is tubules of goblet-like mucinous cells involving the appendiceal wall without stromal response. There might be various component of endocrine and Paneth-like cells with granular eosinophilic cytoplasm as well. Chromogranin and synaptophysin can be positive in these endocrine cells. It's typically positive for CK7 and CK20. From a molecular stand point, alternations of WNT signaling pathway (USP9X, NOTCH1, CTNNA1, CTNNB1, and TRRAP) has been reported. A three tier grading system has been proposed: grade 1 showed tubular or clustered growth >75% and less than 25% of high grade features; while grade 3 showed tubular or clustered growth < 50%. A list of high grade features are shown below:

1.       Complex anastomosing tubules

2.       Cribriform architecture

3.       Confluent solid sheets

4.       Large irregular clusters

5.       Numerous poorly cohesive goblet-like or nonmucinous cells

6.       Single file growth pattern

7.       Single goblet or signet ring-like cells or

adenocarcinomatous glands floating in mucin pools

8.       High grade cytology

9.       Conventional adenocarcinoma

10.   Numerous mitoses with atypical mitotic figures

11.   Necrosis

12.   Desmoplastic stromal reaction

References: https://www.pathologyoutlines.com/topic/appendixgobletcellcarcinoid.html

https://tumourclassification.iarc.who.int/chaptercontent/31/52

Case credit: UCSD pathology

Author: Wangpan Jackson Shi, MD