C78.1 (Secondary malignant neoplasm of mediastinum) compared with D15.2 (Benign neoplasm of mediastinum), from the official CMS tabular data. C78.1 and D15.2 name the same anatomical site (mediastinum) with a different neoplasm behavior.
Same anatomical site, different neoplasm behavior.
Same site — benign neoplasm (mediastinum)
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. C78.1 and D15.2 name the same anatomical site (mediastinum) 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.
| C78.1Secondary malignant neoplasm of mediastinum | D15.2Benign neoplasm of mediastinum | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | C00-D49 — Neoplasms (C00-D49) | C00-D49 — Neoplasms (C00-D49) |
| Definition | Secondary malignant neoplasm of mediastinum is a billable ICD-10-CM diagnosis code (C78.1). | Benign neoplasm of mediastinum is a billable ICD-10-CM diagnosis code (D15.2). |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources