C78.1 Secondary malignant neoplasm of mediastinum

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applies from C78 Secondary malignant neoplasm of respiratory and digestive organs

Excludes1 (never code together)

• secondary carcinoid tumors of liver (C7B.02)
• secondary carcinoid tumors of peritoneum (C7B.04)

Excludes2 (not included here)

• lymph node metastases (C77.0)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 17 — Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic
• CMS-HCC V22: HCC 8 — Metastatic Cancer and Acute Leukemia
• RxHCC V08: HCC 18 — Secondary Cancer of Lung, Liver, Brain, and Other Sites
• ESRD V24: HCC 8

MS-DRG index

Defines the logic of DRG(s) 180-182 in MDC 04.

Approximate ICD-9-CM (GEMs)

• 197.1 Secondary malignant neoplasm of mediastinum

Nearby codes

• C78 Secondary malignant neoplasm of respiratory and digestive organs
• C78.0 Secondary malignant neoplasm of lung
• C78.00 Secondary malignant neoplasm of unspecified lung
• C78.01 Secondary malignant neoplasm of right lung
• C78.02 Secondary malignant neoplasm of left lung
• C78.1 Secondary malignant neoplasm of mediastinum (this code)
• C78.2 Secondary malignant neoplasm of pleura
• C78.3 Secondary malignant neoplasm of other and unspecified respiratory organs
• C78.30 Secondary malignant neoplasm of unspecified respiratory organ
• C78.39 Secondary malignant neoplasm of other respiratory organs
• C78.4 Secondary malignant neoplasm of small intestine