Anus & perianal area
General
Staging
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Last author update: 10 December 2020
Last staff update: 6 May 2021
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PubMed Search: Anus and staging[title]
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Cite this page: Gonzalez RS. Staging. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/anusstaging.html. Accessed June 9th, 2023.
Definition / general
- All carcinomas of the anus, including poorly differentiated neuroendocrine carcinomas, are covered by this staging system
Essential features
- AJCC 7th edition staging was sunset on December 31, 2017; as of January 1, 2018, use of the 8th edition is mandatory
Terminology
- Anal cancer: tumors that develop from mucosa that cannot be visualized entirely while gentle traction is placed on the buttocks
- Perianal cancer: tumors that arise within the skin at or distal to the squamous mucocutaneous junction, can be seen entirely with gentle traction on the buttocks and are within 5 cm of the anus
- Older terms for high grade squamous intraepithelial lesion (pTis disease) include carcinoma in situ, Bowen disease, anal intraepithelial neoplasia II-III and high grade anal intraepithelial neoplasia
ICD coding
- ICD-10: C21.0 - Malignant neoplasm of anus, unspecified
Primary tumor (pT)
- TX: Primary tumor not assessed
- T0: No evidence of primary tumor
- Tis: High grade squamous intraepithelial lesion
- T1: Tumor ≤ 2 cm
- T2: Tumor > 2 cm but ≤ 5 cm
- T3: Tumor > 5 cm
- T4: Tumor of any size invading adjacent organ(s), such as the vagina, urethra or bladder
Regional lymph nodes (pN)
- NX: Regional lymph nodes cannot be assessed
- N0: No regional lymph node metastasis
- N1: Metastasis in inguinal, mesorectal, internal iliac or external iliac nodes
- N1a: Metastasis in inguinal, mesorectal or internal iliac nodes
- N1b: Metastasis in external iliac lymph nodes
- N1c: Metastasis in external iliac with any N1a nodes
- Notes:
- Superior rectal (hemorrhoidal) lymph nodes are also considered regional lymph nodes, though not specifically mentioned in the pN criteria
Prefixes
- y: preoperative radiotherapy or chemotherapy
- r: recurrent tumor stage
Stage grouping
- Stage 0:
Tis
N0
M0
- Stage I:
T1
N0
M0
- Stage IIA:
T2
N0
M0
- Stage IIB:
T3
N0
M0
- Stage IIIA:
T1 - T2
N1
M0
- Stage IIIB:
T4
N0
M0
- Stage IIIC:
T3 - T4
N1
M0
- Stage IV:
any T
any N
M1
Registry data collection variables
- Tumor location
- HIV status
- Gender
- Grade
- HPV status and p16 or p18 expression
Histologic grade
- GX: Grade cannot be assessed
- G1: Well differentiated (low grade)
- G2: Moderately differentiated (low grade)
- G3: Poorly differentiated (high grade)
- G4: Undifferentiated (high grade)
Board review style question #1
Which of the following criteria characterizes a malignancy as an anal, rather than a perianal, tumor?
- Arises distal to the squamous mucocutaneous junction
- Cannot be entirely visualized after gentle traction on the buttocks
- Squamous cell or basal cell carcinoma histologically
- Visible only on colonoscopy
Board review style answer #1
B. Cannot be entirely visualized after gentle traction on the buttocks
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Staging
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