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Record the behavior of the tumor being reported.  The fifth digit of the morphology code is the behavior code. 

Instructions for Coding·        Code

• Code 3 if any invasion is present, no matter how limited.

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• If the specimen is from a metastatic site, code the histology of the metastatic site and code 3 for behavior

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• Gastro-intestinal stromal tumors (GIST) and thyomas are frquently non-malignant. However, they must be abstracted and assigned a Behavior Code of 3 if they are noted to have multiple foci, metastasis, or positive lymph nodes.

Note: The ICD-O-3 behavior code for juvenile astrocytoma (9421/1) is coded as 3.  Refer to the section "Case Reporting Requirements."

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