C79.89 (Secondary malignant neoplasm of other specified sites) compared with D04.7 (Carcinoma in situ of skin of lower limb, including hip), from the official CMS tabular data. C79.89 and D04.7 name the same anatomical site (ankle) with a different neoplasm behavior. MedCoder-derived
Same anatomical site, different neoplasm behavior.
Same site — carcinoma in situ (ankle)
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 D04.7 name the same anatomical site (ankle) with a different neoplasm behavior.
From the CMS/CDC 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 | D04.7Carcinoma in situ of skin of lower limb, including hip | |
|---|---|---|
| Billing status | Billable | Non-billable header |
| Classification | C00-D49 — Neoplasms (C00-D49) | C00-D49 — Neoplasms (C00-D49) |
| Definition | Secondary malignant neoplasm of other specified sites is a billable ICD-10-CM diagnosis code (C79.89). | Carcinoma in situ of skin of lower limb, including hip is a non-billable ICD-10-CM category code (D04.7). |
| Includes | — | Bowen's disease erythroplasia grade III intraepithelial neoplasia Queyrat's erythroplasia |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources