C00.6 (Malignant neoplasm of commissure of lip, unspecified) compared with C79.89 (Secondary malignant neoplasm of other specified sites), from the official CMS tabular data. C00.6 and C79.89 name the same anatomical site (commissure) with a different neoplasm behavior.
Same anatomical site, different neoplasm behavior.
Same site — secondary malignancy (commissure)
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. C00.6 and C79.89 name the same anatomical site (commissure) 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.
| C00.6Malignant neoplasm of commissure of lip, unspecified | C79.89Secondary malignant neoplasm of other specified sites | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | C00-D49 — Neoplasms (C00-D49) | C00-D49 — Neoplasms (C00-D49) |
| Definition | Malignant neoplasm of commissure of lip, unspecified is a billable ICD-10-CM diagnosis code (C00.6). | Secondary malignant neoplasm of other specified sites is a billable ICD-10-CM diagnosis code (C79.89). |
| Use additional code | code to identify: alcohol abuse and dependence (F10.-) history of tobacco dependence (Z87.891) | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources