Appendix

• AJCC 7th edition staging was sunset on December 31, 2017; as of January 1, 2018, use of the 8th edition is mandatory
• AJCC 9th edition was released in 2023, with minimal changes from the 8th edition

• 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 or 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)
• T1 and T2 are applicable to HAMN

• NX: regional lymph nodes cannot be assessed
• N0: no tumor involvement of regional lymph node(s)
• N1: tumor involvement of 1 to 3 regional lymph nodes (tumor in lymph node measuring ≥ 0.2 mm) or any number of tumor deposit(s)
  • N1a: tumor involvement of 1 regional lymph node
  • N1b: tumor involvement of 2 or 3 regional lymph nodes
  • N1c: no tumor involvement of regional lymph nodes but there are tumor deposits in the subserosa or mesentery
• N2: tumor involvement of 4 or more regional lymph nodes

Notes:

• Regional lymph nodes include ileocolic nodes

• cM0: no distant metastasis
• cM1: distant metastasis
  • cM1c: metastasis to sites other than peritoneum
• pM1: microscopic confirmation of distant metastasis
  • pM1a: intraperitoneal acellular mucin, without identifiable tumor cells in the disseminated peritoneal mucinous deposits
  • pM1b: intraperitoneal metastasis only, including peritoneal mucinous deposits containing tumor cells
  • pM1c: microscopic confirmation of metastasis to sites other than peritoneum

Notes:

• For specimens containing acellular mucin without identifiable tumor cells, efforts should be made to obtain additional tissue for thorough histologic examination to evaluate for cellularity

Stage group 0:	Tis or Tis(LAMN)	N0	M0	any G
Stage group I:	T1 - 2	N0	M0	any G
Stage group IIA:	T3	N0	M0	any G
Stage group IIB:	T4a	N0	M0	any G
Stage group IIC:	T4b	N0	M0	any G
Stage group IIIA:	T1 - 2	N1	M0	any G
Stage group IIIB:	T3 - 4	N1	M0	any G
Stage group IIIC:	any T	N2	M0	any G
Stage group IVA:	any T	any N	M1a	any G
	any T	any N	M1b	G1
Stage group IVB:	any T	any N	M1b	G2, G3, GX
Stage group IVC:	any T	any N	M1c	any G

• GX: grade cannot be assessed
• G1: well differentiated
• G2: moderately differentiated
• G3: poorly differentiated

Notes:

• In rare cases of discordance in primary and metastatic histological grade, the grade of metastatic disease is utilized for stage group assignment

• Large cell neuroendocrine carcinoma
• Undifferentiated carcinoma
• Small cell neuroendocrine carcinoma
• Squamous cell carcinoma
• Adenocarcinoma
• Mixed neuroendocrine nonneuroendocrine neoplasm
• Goblet cell adenocarcinoma
• Low grade appendiceal mucinous neoplasm
• High grade appendiceal mucinous neoplasm
• Mucinous adenocarcinoma
• Signet ring cell carcinoma

• 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

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 adenocarcinoma

B. When a tumor has cellular intraperitoneal metastases. Such cases are stage IV and they may be subclassified as IVA or IVB depending on the tumor grade. Answer C is incorrect because tumor grade does not impact pT category staging of appendiceal adenocarcinomas. Answers A and D are incorrect because they do not influence staging of appendiceal adenocarcinomas.

Comment Here

Reference: Appendix - Staging - carcinoma

What is the difference in AJCC staging parameters for low grade apendiceal mucinous neoplasm (LAMN) and high grade apendiceal mucinous neoplasm (HAMN)?

1. LAMN cannot be pM1a but HAMN can
2. LAMN cannot be pN1 but HAMN can
3. LAMN cannot be pT1 / 2 but HAMN can
4. LAMN cannot be pT4a but HAMN can

C. LAMN cannot be pT1 / 2 but HAMN can. LAMN is reported as pTis(LAMN) if bound by muscularis propria, whereas HAMN would be pT1 or pT2 in the same situation, depending on whether submucosa or muscularis propria is involved. Answer A is incorrect because both LAMN and HAMN can be pM1a. Answer B is incorrect because both LAMN and HAMN can theoretically be pN1 (though this is extraordinarily unlikely). Answer D is incorrect because both LAMN and HAMN can be pT4a.

Comment Here

Reference: Appendix - Staging - carcinoma