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Table 1 Classification of epithelial neoplasia of the appendix

From: Low-grade appendiceal mucinous neoplasm and endometriosis of the appendix

Terminology

Defining factors

Secondary defining factors

Adenoma

Tubulor, tubulovillous, or villous adenoma with low- to high-grade dysplasia

 

Low-grade appendiceal mucinous adenoma

Mucinous neoplasm with low-grade cytologic atypia

Presence of ≥ 1 of the following:

-Submucosa fibrosis

-Loss of muscularis mucosae

-Diverticulum-like growth through appendiceal wall

-Dissection of acellular mucin

-Mucin outside the appendix

-Appendiceal rupture

Mucinous adenocarcinoma

Mucinous neoplasm with evidence of cellular invasion past the epithelial layer