C80.1 (Malignant (primary) neoplasm, unspecified) compared with D09.9 (Carcinoma in situ, unspecified), from the official CMS tabular data. C80.1 and D09.9 name the same anatomical site (unspecified site) with a different neoplasm behavior.
Same anatomical site, different neoplasm behavior.
Same site — carcinoma in situ (unspecified site)
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. C80.1 and D09.9 name the same anatomical site (unspecified site) 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.
| C80.1Malignant (primary) neoplasm, unspecified | D09.9Carcinoma in situ, unspecified | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | C00-D49 — Neoplasms | C00-D49 — Neoplasms |
| Definition | Malignant (primary) neoplasm, unspecified is a billable ICD-10-CM diagnosis code (C80.1). | Carcinoma in situ, unspecified is a billable ICD-10-CM diagnosis code (D09.9). |
| Includes | Cancer NOS Cancer unspecified site (primary) Carcinoma unspecified site (primary) Malignancy unspecified site (primary) | 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