Collaborative Stage

Note 1: Liver metastasis implies the presence of tumor inside the liver parenchyma as one or more nodules. Adherence to the liver capsule, even if extensive, should not be considered liver metastasis. Code direct adherence to the liver in CS Extension code 570.
Note 2: When a patient has more than one area of gastrointestinal stromal tumor (GIST), it is important to try to distinguish between intra-abdominal metastasis and tumor multiplicity. Distant metastases are relatively rare in GISTs, but they are increasingly detected with sophisticated radiological studies. Intra-abdominal metastasis will present as tumor involvement in the abdominal cavity outside the main tumor mass, in the peritoneum, omentum, serosae of organs, and the cul-de-sac, among other areas. Code this form of metastasis in CS Mets at DX.

Tumor multiplicity, in contrast, will present with anatomically separate, multiple tumors of different sizes arising independently in the GI tract. This form of tumor multiplicity usually will be seen in patients with neurofibromatosis type 1 or familial GIST syndrome, but in rare instances may be seen in patients without these conditions. This form of multiplicity should not be coded as metastasis, but the presence of multiple tumors should be coded in CS Site-Specific Factor 15, Tumor Multiplicity.

When a solitary omental or mesenteric tumor mass is found with a primary GIST elsewhere, do not code this as a metastasis. Code it as multiple tumors in CS Site-Specific Factor 15, Tumor Multiplicity.

When multiple tumor areas are present and it is not stated whether these are metastases or independent tumors, consult with a physician if possible to determine how to code them. If a decision cannot be made, code as 99.
Note 3: Peritoneal nodules are not excluded as a staging component for M1 disease of GISTAppendix and may be coded in code 48. All cases with code 60 in CSv2: V0201, V0202 should be reviewed to determine if they could be recoded to code 48 or 50.
Note 4: Involvement of superior mesenteric node(s) is coded 08. Inferior mesenteric node(s) are included in code 10. Mesenteric node(s), NOS are coded in CS Lymph Nodes.

Code	Description	TNM 7 Map	TNM 6 Map	SS77 Map	SS2000 Map
00	No distant metastasis	M0	NA	NONE	NONE
08	Superior mesenteric lymph node(s)	M1	NA	RN	D
10	Distant lymph node(s) other than those in code 08 (Includes inferior mesenteric lymph node(s)) Distant lymph node(s), NOS	M1	NA	D	D
40	OBSOLETE DATA RETAINED V0200 See codes 45 and 60 Distant metastases except distant lymph node(s) (codes 08-10) Distant metastasis, NOS Carcinomatosis	ERROR	NA	D	D
45	OBSOLETE DATA CONVERTED V0203 See codes 48 Distant metastases except distant lymph node(s) (code 10) or peritoneal spread Carcinomatosis	ERROR	ERROR	ERROR	ERROR
48	Distant metastasis including: Peritoneal nodules Liver parenchymal nodules Carcinomatosis	M1	NA	D	D
50	48 + (08 and/or 10) Distant metastasis plus distant lymph node(s)	M1	NA	D	D
60	DATA REVIEWED V0203 Peritoneal nodules are not excluded as a staging component for M1 disease of GISTAppendix and may be coded in code 48. Review all cases with code 60 in CSv2: V0201, V0202 to determine if they should be recoded to code 48 or 50. Distant metastasis, NOS Stated as M1 with no other information on distant metastasis	M1	NA	D	D
99	Unknown; distant metastasis not stated Distant metastasis cannot be assessed Not documented in patient record	M0	NA	U	U

GISTAppendix

CS Mets at DX