California Cancer Reporting System Standards Volume I: Abstracting and Coding Procedures
Unspecified malignancies are those malignancies in which a specific histologic type has not been identified.
Enter the code for neoplasm (8000) for unspecific terms such as "malignant tumor," "malignant neoplasm", and "cancer".
Use code 8001 (malignant cells, NOS), if a diagnosis is based only on a cytology report stating "malignant cells".
Do not use code 9990 for a clinically malignant tumor that has not been microscopically confirmed.
See also Section IV.2.