C79.81 (Secondary malignant neoplasm of breast) compared with D05 (Carcinoma in situ of breast), from the official CMS tabular data. C79.81 and D05 name the same anatomical site (areola) with a different neoplasm behavior. MedCoder-derived
Same anatomical site, different neoplasm behavior.
Same site — carcinoma in situ (areola)
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. C79.81 and D05 name the same anatomical site (areola) 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.
| C79.81Secondary malignant neoplasm of breast | D05Carcinoma in situ of breast | |
|---|---|---|
| Billing status | Billable | Non-billable header |
| Classification | C00-D49 — Neoplasms | C00-D49 — Neoplasms |
| Definition | Secondary malignant neoplasm of breast is a billable ICD-10-CM diagnosis code (C79.81). | Carcinoma in situ of breast is a non-billable ICD-10-CM category code (D05). |
| 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