C78.1
BillableSecondary malignant neoplasm of mediastinum
HCC Category Mapping
V28HCC 17 — Metastatic Cancer and Acute Leukemia
0.368V24HCC 8 — Metastatic Cancer and Acute Leukemia
2.484ESRDHCC 8 — Metastatic Cancer and Acute Leukemia
0.000RxHCCHCC 18 — Metastatic Cancer to Lung and Other Respiratory Sites
0.000What This Code Means
Cancer that has spread to the mediastinum, which is the central compartment of the chest cavity between the lungs.
Coding Tips
- •The mediastinum is a specific anatomical space; do not confuse with lung parenchymal involvement (C78.0x codes)
- •Code the primary malignancy separately; this code indicates secondary involvement of the mediastinal space
Clinical Significance
Secondary malignant neoplasm of the mediastinum indicates cancer has metastasized to the central chest compartment between the lungs. Mediastinal metastases can compress vital structures including the heart, great vessels, trachea, and esophagus, creating life-threatening complications. This is a distinct anatomical location from lung parenchymal or pleural disease.
Documentation Requirements
- ✓Primary cancer site documented and coded separately
- ✓Imaging confirmation (CT chest, PET scan) showing mediastinal involvement
- ✓Specification of anterior, middle, or posterior mediastinal involvement if available
- ✓Documentation of any mass effect on adjacent structures — superior vena cava syndrome, tracheal compression, esophageal obstruction
- ✓Whether mediastinal lymphadenopathy is present versus direct tissue invasion
Commonly Confused Codes
C78.01/C78.02 — Secondary malignant neoplasm of lung; mediastinal and lung parenchymal metastases are anatomically distinctC78.2 — Secondary malignant neoplasm of pleura; pleural disease involves the lung lining, not the mediastinal spaceC38.1-C38.3 — Primary malignant neoplasm of mediastinum; verify this is secondary, not primary mediastinal cancerC77.1 — Secondary neoplasm of intrathoracic lymph nodes; lymph node metastasis is coded differently from direct mediastinal invasion
Code Hierarchy
└C78Secondary malignant neoplasm of respiratory and digestive organs└C78.1Secondary malignant neoplasm of mediastinum
└C78.1Secondary malignant neoplasm of mediastinum