C73 (Malignant neoplasm of thyroid gland) compared with D44.0 (Neoplasm of uncertain behavior of thyroid gland), from the official CMS tabular data. C73 and D44.0 name the same anatomical site (thyroglossal duct) with a different neoplasm behavior. MedCoder-derived
Same anatomical site, different neoplasm behavior.
Same site — uncertain behavior (thyroglossal duct)
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. C73 and D44.0 name the same anatomical site (thyroglossal duct) 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.
| C73Malignant neoplasm of thyroid gland | D44.0Neoplasm of uncertain behavior of thyroid gland | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | C00-D49 — Neoplasms (C00-D49) | C00-D49 — Neoplasms (C00-D49) |
| Definition | Malignant neoplasm of thyroid gland is a billable ICD-10-CM diagnosis code (C73). | Neoplasm of uncertain behavior of thyroid gland is a billable ICD-10-CM diagnosis code (D44.0). |
| Use additional code | code to identify any functional activity | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources