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Small bowel (small intestine)

Other malignancies


Reviewer: Hanni Gulwani, M.D. (see Reviewers page)
Revised: 22 December 2012, last major update August 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.


● Staging system also used for GIST of esophagus, colorectum, mesentery and peritoneum

Primary tumor (T)

TX: Primary tumor cannot be assessed
T0: No evidence for primary tumor
T1: Tumor 2 cm or less
T2: Tumor more than 2 cm but not more than 5 cm
T3: Tumor more than 5 cm but not more than 10 cm
T4: Tumor more than 10 cm in greatest dimension

● For ruptured tumors, use radiologic data to estimate tumor size

Regional lymph nodes (N)

N0: No regional lymph node metastasis
N1: Regional lymph node metastasis

● Nodal metastases are extremely rare in GIST, so there is no routine indication for lymph node biopsy or lymph node dissection
● Use N0/pN0 if no information on nodal status; do not use NX

Distant Metastasis (M)

M0: No distant metastasis
M1: Distant metastasis (specify site, if known)

● Most GISTs metastasize to intra-abdominal soft tissue or liver
● Intra-abdominal metastasis refers to tumor involvement in abdominal cavity away from the primary mass, usually to serosal surfaces of abdomen, pelvis, retroperitoneum
● Multiple primary tumors are associated with neurofibromatosis type 1 or familial GIST syndrome and should not be considered intraabdominal metastasis, although rare cases of multiple independent GISTs at different GI locations have been reported
● If no primary GI GIST is identified, solitary omental, mesenteric, pelvic or retroperitoneal GISTs should be considered primary tumors
● A liver metastasis implies metastatic tumor inside the liver parenchyma as 1 or more nodules, but adherence to liver capsule, even if extensive, should not be considered liver metastasis

Anatomic stage / prognostic groups

Stage IA: T1-2 N0 M0 and low mitotic rate
Stage IB: T3 N0 M0 and low mitotic rate
Stage II: T1-2 N0 M0 and high mitotic rate or T4 N0 M0 and low mitotic rate
Stage IIIA: T1 N0 M0 and high mitotic rate OR T4 N0 M0 and low mitotic rate
Stage IIIB: T2-4 N0 M0 and high mitotic rate
Stage IV: N1 or M1

● Low mitotic rate: 5 or fewer per 50 HPF
● High mitotic rate: over 5 per 50 HPF
● The required total count of mitoses is per 5 mm2 on the glass slide (50 HPF for older microscopes, 20 HPF for newer microscopes)


Guidelines for risk assessment of primary gastrointestinal stromal tumor

Additional references

Protocol for the Examination of Specimens From Patients With GIST (pdf)

End of Small bowel (small intestine) > Other malignancies > Staging-GIST

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