C79.89 (Secondary malignant neoplasm of other specified sites) compared with D10.30 (Benign neoplasm of unspecified part of mouth), from the official CMS tabular data. C79.89 and D10.30 name the same anatomical site (cavity) with a different neoplasm behavior.
Same anatomical site, different neoplasm behavior.
Same site — benign neoplasm (cavity)
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
Same site, different neoplasm behavior. C79.89 and D10.30 name the same anatomical site (cavity) 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.
| C79.89Secondary malignant neoplasm of other specified sites | D10.30Benign neoplasm of unspecified part of mouth | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | C00-D49 — Neoplasms | C00-D49 — Neoplasms |
| Definition | Secondary malignant neoplasm of other specified sites is a billable ICD-10-CM diagnosis code (C79.89). | Benign neoplasm of unspecified part of mouth is a billable ICD-10-CM diagnosis code (D10.30). |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources