Non-malignant Brain Tumors (Behavior /0/1)

The reason for reporting benign and borderline brain and CNS tumors is

• Benign and borderline CNS tumors disrupt normal function similar to that caused by malignant CNS tumors.
• Location of a CNS tumor is as important as tumor behavior (benign or malignant) for morbidity and mortality.

CNS tumors, especially benign brain tumors, are most often diagnosed clinically via scans (either incidentally or based on presenting symptoms) and can be histologically confirmed via biopsy or excision. Unusual and ambiguous terminology used either on scans or pathology reports in the diagnosis of CNS tumors makes it difficult to determine if a case is reportable, and if it is reportable, to determine site and histology. If the final clinical or pathologic diagnosis is a CNS mass or neoplasm, there must be an ICD-O-3 code to be reportable. If there is no ICD-O-3 code, do not report the case.

Diagnoses like hypodense mass or cystic mass are not reportable even for CNS sites. Non-malignant tumors are only reportable for CNS sites.

A benign meningioma with the site listed as skull should be coded to the cerebral meninges. The meninges are between the skull and the intracranial tissues. A meningioma which originates in the meninges can invade the skull. The skull invasion does not make the meningioma malignant. Do NOT code primary site to Brain, NOS, or any subsites (C710-C719).

If the ONLY diagnosis available (clinical or pathological) is CNS "tumor" or "neoplasm" this is reportable and is coded 8000/1.

Note: For many data items, there are specific codes that will capture the benign/borderline cases when applicable. For example, Summary Stage, EOD and the SSDIs, have specific codes for the benign/borderline tumors.

Brain Tumors: Primary vs Metastatic

Primary brain tumors begin in the brain and tend to stay in the brain. Metastatic brain tumors begin as a cancer elsewhere in the body and spread, or metastasize, to the brain. Metastatic brain tumors are the most common type of brain tumor, with an annual incidence more than four times greater than that of primary brain tumors. The cancers that most commonly metastasize to the brain are breast and lung cancer.

Primary brain tumors are different from other cancers in several ways. One important factor is that brain tumors develop within the confined space of the skull where there is little extra room into which they may grow. Thus, even a small tumor can seriously affect normal brain function.

Also, brain tumors have relatively little tendency to metastasize outside the nervous system regardless of histologic type. Therefore, the terms "benign" and "malignant" have different meanings from those referring to abnormal growths elsewhere in the body. For brain tumor, benign means the tumor is relatively slow-growing; malignant means the tumor is aggressive or fast-growing. Most histologic types of CNS tumors can be either benign or malignant. Remember that a benign CNS tumor can become just as dangerous as a malignant one if the tumor presses on a vital area of brain tissue.

Updated: September 23, 2026