C31.0 (Malignant neoplasm of maxillary sinus) compared with D49.1 (Neoplasm of unspecified behavior of respiratory system), from the official CMS tabular data. C31.0 and D49.1 name the same anatomical site (antrum) with a different neoplasm behavior.
Same anatomical site, different neoplasm behavior.
Same site — primary malignancy (antrum)
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. D49.1 and C31.0 name the same anatomical site (antrum) 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.
| C31.0Malignant neoplasm of maxillary sinus | D49.1Neoplasm of unspecified behavior of respiratory system | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | C00-D49 — Neoplasms | C00-D49 — Neoplasms |
| Definition | Malignant neoplasm of maxillary sinus is a billable ICD-10-CM diagnosis code (C31.0). | Neoplasm of unspecified behavior of respiratory system is a billable ICD-10-CM diagnosis code (D49.1). |
| Includes | malignant neoplasm of middle ear Malignant neoplasm of antrum (Highmore) (maxillary) | 'growth' NOS neoplasm NOS new growth NOS tumor NOS |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources