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C79.40 vs D33.9

C79.40 (Secondary malignant neoplasm of unspecified part of nervous system) compared with D33.9 (Benign neoplasm of central nervous system, unspecified), from the official CMS tabular data. C79.40 and D33.9 name the same anatomical site (nervous system) with a different neoplasm behavior.

Relationship

Informational

Neoplasm table relationship

C79.40
Secondary malignant neoplasm of unspecified part of nervous system
↔
D33.9
Benign neoplasm of central nervous system, unspecified

Same anatomical site, different neoplasm behavior.

Same site — benign neoplasm (nervous system)

The behavior documented for the site — malignant primary, secondary, carcinoma in situ, benign, uncertain or unspecified — decides which column of the neoplasm table, and therefore which code, applies.

Source: CMS Table of Neoplasms

Can these codes be reported together?

Same site, different neoplasm behavior. C79.40 and D33.9 name the same anatomical site (nervous system) with a different neoplasm behavior.

From the CMS Table of Neoplasms: the behavior documented for that site — malignant primary, secondary, carcinoma in situ, benign, uncertain or unspecified — decides which column, and therefore which code, applies.

Side by side

C79.40Secondary malignant neoplasm of unspecified part of nervous systemD33.9Benign neoplasm of central nervous system, unspecified
Billing statusBillableBillable
ClassificationC00-D49 — NeoplasmsC00-D49 — Neoplasms
DefinitionSecondary malignant neoplasm of unspecified part of nervous system is a billable ICD-10-CM diagnosis code (C79.40).Benign neoplasm of central nervous system, unspecified is a billable ICD-10-CM diagnosis code (D33.9).
Includes—
Benign neoplasm of nervous system (central) NOS
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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources