Appendix
Miscellaneous
Staging

Author: Raul S. Gonzalez, M.D.
Deputy Editor Review: Debra Zynger, M.D.

Revised: 10 July 2018, last major update May 2018

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: Staging appendix "loattrfree full text"[sb]
Cite this page: Gonzalez, R.S. Staging. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/appendixstaging.html. Accessed July 17th, 2018.

Pathologic TNM staging of carcinomas of the appendix, AJCC 8th edition
Definition / general
  • All carcinomas of the appendix, including poorly differentiated neuroendocrine carcinomas, are covered by this staging system
  • Low grade appendiceal mucinous neoplasm (LAMN) and goblet cell carcinoids are also covered by this staging system
  • Not covered by this staging system are conventional well differentiated neuroendocrine tumors at this location (use the neuroendocrine tumors staging system instead, see CAP Protocol)
Essential features
  • AJCC 7th edition staging was sunset on December 31, 2017; as of January 1, 2018, use of the 8th edition is mandatory
ICD-10 coding
  • C18.1: malignant neoplasm of appendix
Primary tumor (pT)
  • TX: primary tumor cannot be assessed
  • T0: no evidence of primary tumor
  • Tis: carcinoma in situ (intramucosal carcinoma; invasion of the lamina propria or extension into but not through the muscularis mucosae)
  • Tis(LAMN): low grade appendiceal mucinous neoplasm confined by the muscularis propria; acellular mucin or mucinous epithelium may invade into the muscularis propria
  • T1: tumor invades the submucosa (through the muscularis mucosa but not into the muscularis propria)
  • T2: tumor invades the muscularis propria
  • T3: tumor invades through the muscularis propria into the subserosa of the mesoappendix
  • T4: tumor invades the visceral peritoneum, including the acellular mucin or mucinous epithelium involving the serosa of the appendix or mesoappendix or directly invades adjacent organs or structures
    • T4a: tumor invades through the visceral peritoneum, including the acellular mucin or mucinous epithelium involving the serosa of the appendix or serosa of the mesoappendix
    • T4b: tumor directly invades or adheres to adjacent organs or structures
  • Notes: T1 and T2 are not applicable to LAMN; acellular mucin or mucinous epithelium that extends into the subserosa or serosa should be classified as T3 or T4a, respectively (Hum Pathol 2017;69:81)
Regional lymph nodes (pN)
  • NX: regional lymph nodes cannot be assessed
  • N0: no regional lymph node metastasis
  • N1: one to three regional lymph nodes are positive (tumor in lymph node measuring > 0.2 mm) or presence of tumor deposit(s) with negative lymph nodes
    • N1a: one regional lymph node is positive
    • N1b: two or three regional lymph nodes are positive
    • N1c: no regional lymph nodes are positive but there are tumor deposits in the subserosa or mesentery
  • N2: four or more regional lymph nodes are positive
  • Notes: regional lymph nodes include ileocolic nodes
Distant metastasis (pM)
  • M0: no distant metastasis
  • M1: distant metastasis
    • M1a: intraperitoneal acellular mucin, without identifiable tumor cells in the disseminated peritoneal mucinous deposits
    • M1b: intraperitoneal metastasis only, including peritoneal mucinous deposits containing tumor cells
    • M1c: metastasis to sites other than peritoneum
  • Notes: for specimens consisting of acellular mucin without identifiable tumor cells, additional tissue should be submitted if available, to thoroughly evaluate for the presence of tumor cells
Prefixes
  • y: preoperative radiotherapy or chemotherapy
  • r: recurrent tumor stage
Stage grouping
  • Stage 0:Tis N0 M0  
  •  Tis(LAMN) N0 M0  
  • Stage I:T1 - 2 N0 M0  
  • Stage IIA:T3 N0 M0  
  • Stage IIB:T4a N0 M0  
  • Stage IIC:T4b N0 M0  
  • Stage IIIA:T1 - T2 N1 M0  
  • Stage IIIB:T3 - T4 N1 M0  
  • Stage IIIC:any T N2 M0  
  • Stage IVA:any T any N M1a  
  •  any T any N M1bG1
  • Stage IVB:any T any N M1b G2, G3, GX
  • Stage IVC:any T any N M1c any G

Registry data collection variables
  • Grade
  • CEA levels
  • Tumor deposits
  • Lymphovascular invasion
  • Perineural invasion
Histologic grade
  • GX: grade cannot be assessed
  • G1: well differentiated
  • G2: moderately differentiated
  • G3: poorly differentiated
Histopathologic type
  • Adenocarcinoma in situ
  • Low grade appendiceal mucinous neoplasm
  • Adenocarcinoma
  • Mucinous carcinoma (> 50% mucinous carcinoma)
  • Signet ring cell carcinoma (> 50% signet ring cells)
  • Undifferentiated carcinoma
  • Goblet cell carcinoid
  • Mixed adenoneuroendocrine carcinoma
  • Carcinoma, NOS
Residual tumor
  • R0: complete resection, margins histologically negative, no residual tumor left after resection
  • R1: incomplete resection, margins histologically involved, microscopic tumor remains after resection of gross disease (relevant to resection margins that are microscopically involved by tumor)
  • R2: incomplete resection, margins involved or gross disease remains
Board review question #1
Using AJCC staging criteria for adenocarcinomas of the appendix, at what point is tumor grade utilized (along with pT, pN and pM status) in order to assign overall combined tumor stage?

  1. When a tumor extends to the surgical resection margin
  2. When a tumor has cellular intraperitoneal metastases
  3. When a tumor involves the muscularis propria
  4. When a tumor is a goblet cell carcinoid
Board review answer #1
B. When a tumor has cellular intraperitoneal metastases