C09.0 (Malignant neoplasm of tonsillar fossa) compared with D49.0 (Neoplasm of unspecified behavior of digestive system), from the official CMS tabular data. C09.0 and D49.0 name the same anatomical site (fossa) with a different neoplasm behavior. MedCoder-derived
Same anatomical site, different neoplasm behavior.
Same site — unspecified behavior (fossa)
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. C09.0 and D49.0 name the same anatomical site (fossa) 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.
| C09.0Malignant neoplasm of tonsillar fossa | D49.0Neoplasm of unspecified behavior of digestive system | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | C00-D49 — Neoplasms | C00-D49 — Neoplasms |
| Definition | Malignant neoplasm of tonsillar fossa is a billable ICD-10-CM diagnosis code (C09.0). | Neoplasm of unspecified behavior of digestive system is a billable ICD-10-CM diagnosis code (D49.0). |
| Includes | — | 'growth' NOS neoplasm NOS new growth NOS tumor NOS |
| Use additional code | code to identify: alcohol abuse and dependence (F10.-) exposure to environmental tobacco smoke (Z77.22) | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources