CS Extension

Notes

**Note 1**: Periosteum is a fibrous membrane that wraps the outer surface of bones. Cortical bone is the dense compact outer layer of the 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 2**: AJCC assigns the T category based on size when bone involvement is limited to the cortex. Involvement through cortical bone is required for assignment of T4a. **Note 3**: 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, 755, 810, or 815 as appropriate to code CS Extension based on a statement of T when no other extension information is available. **Note 4**: Use code 300 for localized tumor only if no information is available to assign code 100, 200, 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
Submucosa
Extension Size Extension Size L L
200 Musculature invaded 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 Adjacent oral cavity Extension Size Extension Size RE RE
535 Cortical bone of mandible
Cortical bone of maxilla
Mandible, NOS
Maxilla, NOS
Cortical bone, NOS (not specified in higher codes)
Bone, NOS (not specified in higher codes)
Extension Size Extension Size D D
600 Oropharynx
Inferior surface of soft palate
Lateral pharyngeal wall
Lingual surface of epiglottis
Vallecula
Extension Size Extension Size RE RE
605 600 + 535

Any structure in 600 plus any structure in 535
Extension Size Extension Size D D
700 OBSOLETE DATA REVIEWED AND CHANGED V0203
CSv2 codes differentiate between involvement of cortical bone and trabecular bone. All CSv1 cases should be reviewed and recoded to 535, 605, or 725 as appropriate.

Extension to adjacent structures:
Mandible
Maxilla
Maxillary antrum (sinus)
Nasal cavity
Skin of face/neck
Tongue
ERROR: ERROR: ERROR: ERROR:
705 Tongue T4a T4a D D
710 Deep (extrinsic) muscle of tongue:
Genioglossus
Hyoglossus
Palatoglossus
Styloglossus
T4a T4a D D
720 OBSOLETE DATA CONVERTED V0200
See code 800

Skull
ERROR: ERROR: ERROR: ERROR:
725 Trabecular bone:
Mandible
Maxilla
Palatine bone
T4a T4a D D
735 Maxillary antrum (sinus)
Nasal cavity
Skin of face/neck
T4a T4a D D
750 OBSOLETE DATA RETAINED V0200

Base of skull
Encases internal carotid artery
Masticator space
Pterygoid plates
ERROR: T4b D D
775 Stated as T4a with no other information on extension T4a T4a D D
788 Specified bone
(Other than maxilla, mandible, and bones in codes 790 and 800)
T4b T4b D D
790 Masticator space
Pterygoid plates
T4b T4b D D
800 Further contiguous extension:
Skull base
Internal carotid artery (encased)
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 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
- For CS Extension codes 100-605 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 100-605 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.