CS Extension

Notes

**Note 1**: Superficial erosion alone of bone/tooth socket by gingival primary is not sufficient to code as bone involvement (code 700). **Note 2**: Periosteum is a fibrous membrane that wraps the outer surface of bones. Mucoperiosteum is a compound structure of mucous membrane and periosteum. Cortical bone is the dense compact outer layer of bone. Trabecular, cancellous, or spongy bone (spongiosa) is a porous network of tissue filling the interior of bone, decreasing weight and allowing room for blood vessels and marrow. **Note 3**: AJCC assigns the T category based on size for involvement of cortical bone. Involvement through cortical bone is required for assignment of T4a. **Note 4**: The assignment of T1, T2 , and T3 categories for tumors of the lip and oral cavity is based on tumor size. A physician's statement of the T category may be used to code 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, other than the physician's statement of the T category. Use codes 405, 410, 415, 775, 810, or 815 as appropriate to code CS Extension based on a statement of T when no other extension information is available. **Note 5**: Use code 300 for localized tumor only if no information is available to assign code 100, 405, 410, or 415.

Code	Description	AJCC 7 T	AJCC 6 T	Summary Stage 1977 T	Summary Stage 2000 T
000	In situ, intraepithelial, noninvasive	Tis	Tis	IS	IS
100	Invasive tumor confined to lamina propria (mucoperiosteum) (stroma)	Extension Size	Extension Size	L	L
300	Localized, NOS	Extension Size	Extension Size	L	L
405	Stated as T1 with no other information on extension	Extension Size	Extension Size	L	L
410	Stated as T2 with no other information on extension	Extension Size	Extension Size	L	L
415	Stated as T3 with no other information on extension	Extension Size	Extension Size	L	L
500	Buccal mucosa (inner cheek) Labial mucosa (inner lip), lip Tongue (mucosa)	Extension Size	Extension Size	RE	RE
535	Cartilage of mandible or maxilla Cortical bone of mandible or maxilla Mandible, NOS Maxilla, NOS Cartilage, NOS Cortical bone, NOS Bone, NOS	Extension Size	Extension Size	RE	RE
550	Facial muscle, NOS Subcutaneous soft tissue of face	Extension Size	Extension Size	RE	RE
600	Lateral pharyngeal wall Tonsillar pillars and fossae Tonsils	Extension Size	Extension Size	RE	RE
650	Soft palate including uvula	Extension Size	Extension Size	RE	RE
720	Deep (extrinsic) muscle of tongue: Genioglossus Hyoglossus Palatoglossus Styloglossus	T4a	T4a	RE	RE
725	Trabecular bone: Mandible Maxilla Palatine bone	T4a	T4a	RE	RE
760	Skin of face	T4a	T4a	D	D
770	Maxillary sinus (antrum)	T4a	T4a	D	D
775	Stated as T4a with no other information on extension	T4a	T4a	RE	RE
788	Specified bone (Other than maxilla, mandible, or bones in codes 795 and 805)	T4b	T4b	D	D
790	OBSOLETE DATA CONVERTED V0200 See code 805 Skull	ERROR:	ERROR:	ERROR:	ERROR:
795	Masticator space Pterygoid plates	T4b	T4b	D	D
800	OBSOLETE DATA RETAINED V0200 Further contiguous extension, including: Masticator space Pterygoid Plates Skull base Encases internal carotid artery	ERROR:	T4b	D	D
805	Further contiguous extension including: Base of skull Internal carotid artery (encased) Skull	T4b	T4b	D	D
810	Stated as T4b with no other information on extension	T4b	T4b	D	D
815	Stated as T4 [NOS] with no other information on extension	T4NOS	T4NOS	RE	RE
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

- For CS Extension codes 100-650 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 100-650 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.