C33 (Malignant neoplasm of trachea) compared with D49.1 (Neoplasm of unspecified behavior of respiratory system), from the official CMS tabular data. C33 and D49.1 name the same anatomical site (cartilage) with a different neoplasm behavior. MedCoder-derived
Same anatomical site, different neoplasm behavior.
Same site — primary malignancy (cartilage)
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 C33 name the same anatomical site (cartilage) 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.
| C33Malignant neoplasm of trachea | D49.1Neoplasm of unspecified behavior of respiratory system | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | C00-D49 — Neoplasms (C00-D49) | C00-D49 — Neoplasms (C00-D49) |
| Definition | Malignant neoplasm of trachea is a billable ICD-10-CM diagnosis code (C33). | Neoplasm of unspecified behavior of respiratory system is a billable ICD-10-CM diagnosis code (D49.1). |
| Includes | malignant neoplasm of middle ear | 'growth' NOS neoplasm NOS new growth NOS tumor NOS |
| Use additional code | code to identify: exposure to environmental tobacco smoke (Z77.22) exposure to tobacco smoke in the perinatal period (P96.81) | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources