# Merkel cell carcinoma staging (AJCC chapter 46)

Source: https://onco.cc/terms/merkel-cell-staging/  
OnCo record `merkel-cell-staging` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Merkel cell carcinoma is staged by tumour size (2 cm is the cut-off), growth into deeper tissue, spread to lymph nodes and, at stage IV, to distant skin or organs.

## Summary

AJCC chapter 46 covers Merkel cell carcinoma and is an 8th edition chapter in the AJCC 2026 table. In the NCI's summary, stage 0 is abnormal Merkel cells in the top layer of skin; stage I is a tumour of 2 cm or less; IIA larger than 2 cm; IIB spread into connective tissue, muscle, cartilage or bone; stage III adds lymph node spread; stage IV is spread to skin away from the primary tumour or to organs such as liver, lung, bone or brain. The stage descriptions are those in the National Cancer Institute's PDQ summary, which follows the AJCC tables.

## Fields

- Kind: Term
- Last checked: 2026-11-04
- Also known as: Merkel cell carcinoma staging; Merkel cell staging

## Sources

- National Cancer Institute, Merkel cell carcinoma treatment (PDQ), patient version: stages: https://www.cancer.gov/types/skin/patient/merkel-cell-treatment-pdq
- American College of Surgeons, AJCC Current Staging System 2026 (which chapters are 8th edition and which Version 9): https://www.facs.org/media/c5ik5tkr/ajcc-current-staging-system-2026.pdf

## Connected records

- terms: [Disease-specific staging and risk systems (FIGO, Ann Arbor, IPI, R-ISS, ELN, IMDC)](https://onco.cc/terms/staging-systems/), [TNM staging](https://onco.cc/terms/tnm-staging/)
- technologies: [Sentinel lymph node biopsy](https://onco.cc/technologies/sentinel-node/)
- cancers: [Merkel cell carcinoma](https://onco.cc/cancers/merkel-cell-carcinoma/)

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JSON: https://onco.cc/api/v1/entities/merkel-cell-staging.json