C37 (Malignant neoplasm of thymus) compared with D09.3 (Carcinoma in situ of thyroid and other endocrine glands), from the official CMS tabular data. C37 and D09.3 name the same anatomical site (thymus) with a different neoplasm behavior. MedCoder-derived
Same anatomical site, different neoplasm behavior.
Same site — primary malignancy (thymus)
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. D09.3 and C37 name the same anatomical site (thymus) 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.
| C37Malignant neoplasm of thymus | D09.3Carcinoma in situ of thyroid and other endocrine glands | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | C00-D49 — Neoplasms (C00-D49) | C00-D49 — Neoplasms (C00-D49) |
| Definition | Malignant neoplasm of thymus is a billable ICD-10-CM diagnosis code (C37). | Carcinoma in situ of thyroid and other endocrine glands is a billable ICD-10-CM diagnosis code (D09.3). |
| Includes | malignant neoplasm of middle ear | 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