MerkelCellSkin - CS Extension

Note 1: In the case of multiple simultaneous tumors, code the tumor with the greatest extension.
Note 2: Skin ulceration does not alter the AJCC T category.
Note 3: In-transit metastasis is coded in CS Lymph Nodes.
Note 4: The assignment of the T1, T2, and T3 categories for Merkel cell carcinomas is based on tumor size. A physician's statement of the T category may be used to code both CS Tumor Size and/or CS Extension if this is the only information in the medical record regarding one or both of these fields. However the two fields are coded independently; for example, the record may document size but not extension. Use codes 600, 610, 620, and 810 as appropriate to code CS Extension based on a statement of T when no other extension information is available.

^ For CS Extension codes 100, 400, 500, 600, 610, and 620 ONLY, the T category for AJCC 7 staging is assigned based on the value of CS Tumor Size as shown in the Extension Size Table for this schema.
* For CS Extension codes 100, 400, 500, 600, 610, and 620 ONLY, the T category for AJCC 6 staging is assigned based on the value of CS Tumor Size as shown in the Extension Size Table for this schema.

Code	Description	TNM 7 Map	TNM 6 Map	SS77 Map	SS2000 Map
000	In situ, intraepidermal, intraepithelial, noninvasive	Tis	Tis	IS	IS
100	Lesion(s) confined to dermis	^	*	L	L
400	Localized, NOS	^	*	L	L
500	Subcutaneous tissue (through entire dermis)	^	*	L	L
600	Stated as T1 with no other information on extension	^	*	L	L
610	Stated as T2 with no other information on extension	^	*	L	L
620	Stated as T3 with no other information on extension	^	*	L	L
680	Fascia	T4	T4	D	RE
700	Underlying cartilage, bone, skeletal muscle	T4	T4	D	RE
800	Further contiguous extension	T4	T4	D	D
810	Stated as T4 with no other information on extension	T4	T4	D	D
950	No evidence of primary tumor	T0	T0	U	U
999	Unknown; extension not stated Primary tumor cannot be assessed Not documented in patient record	TX	TX	U	U