Table 3.

Differences between 7^th Edition (2010) and new 8^th Edition American Joint Committee on Cancer Merkel cell carcinoma staging system

7th Edition Stage	8th Edition Stage	Comments
Clinical and pathological staging are combined in local disease stages I and II	Separate clinical and pathological staging
IA* and IB**	I	Eliminate IB as clinical and pathological staging are separate
IIA* and IIB**	IIA	Eliminate IIB as clinical and pathological staging are separate
IIC	IIB	Rename previous IIC as IIB
IIIA Included:  - occult nodal disease	IIIA Includes:  - occult nodal disease (sn)  - occult nodal disease  - clinically detected nodal disease with unknown primary	Distinguish occult nodal disease identified by sentinel lymph node biopsy without further lymphadenectomy, pN1a(sn), from those who underwent completion lymphadenectomy, pN1a Include clinically detected nodal disease with unknown primary for similar prognostication
IIIB Included:  - clinically detected nodal disease with known primary  - clinically detected nodal disease with unknown primary tumor  - in-transit metastases	IIIB Includes:  - clinically detected nodal disease with known primary  - in-transit metastases without nodal disease  - in-transit metastases with nodal disease Omit:  - clinically detected nodal disease with unknown primary	Continue to combine clinically detected nodal disease with known primary and in-transit disease. Distinguish in-transit metastases without regional nodal disease (revised N2 category) from in-transit metastases with regional nodal disease (new N3 category)
IV	IV	Same

Abbreviations: MCC, Merkel cell carcinoma; sn (sentinel node)

^*“A” distinction in the 7^th Edition of MCC staging of local disease stages I and II designated a negative pathological lymph node evaluation

^**“B” distinction in the 7^th Edition of MCC staging of local disease stages I and II designated that pathological nodal evaluation was not performed