2026 ICD-10-CM Diagnosis Code C77.9Secondary and unspecified malignant neoplasm of lymph node, unspecified
ICD-10-CM Codes›C00–D49›C76-C80›C77
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 18
- Chronic Condition
C77.9 is a billable ICD-10-CM diagnosis code for secondary and unspecified malignant neoplasm of lymph node, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 820 through 825, 840 through 842. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 24 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Secondary malignancies.
For Medicare Advantage risk adjustment, C77.9 maps to CMS-HCC Category 18 (Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid) under the V28 model, adding a risk factor of about 2.341 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
C77.9 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Intergroup rhabdomyosarcoma study post-surgical clinical group finding
- Intergroup rhabdomyosarcoma study post-surgical clinical group IIC: Locally extensive tumor , gross total resection, but microscopic residual disease
- Left regional lymph node metastasis present
- Metastasis to lymph node from adenocarcinoma
- Metastatic malignant neoplasm to lymph node
- Metastatic squamous cell carcinoma to lymph node
- Metastatic well-differentiated neuroendocrine tumor
- Metastatic well-differentiated neuroendocrine tumor to regional lymph node
- Regional lymph node metastasis present
- Right regional lymph node metastasis present
- Tumor metastasis to non-regional lymph nodes present
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Table of NeoplasmsClinical
Patient EducationClinical
Cancer
Cancer is not just one disease but many diseases. Cancer begins in your cells, which are the building blocks of your body. Usually, your body forms new cells as needed, replacing old cells that die. Sometimes this process goes wrong. New cells grow even when you don't need them, and old cells don't die when they should.
The full article covers:
- What is cancer?
- What are the types of cancer?
- How does cancer develop?
- What are the symptoms of cancer?
- How is cancer diagnosed?
- What are the treatments for cancer?
- Can cancer be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert C77.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C77.9Overview
Is C77.9 (Secondary and unspecified malignant neoplasm of lymph nodes) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report secondary and unspecified malignant neoplasm of lymph node, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does C77.9 group to?
When secondary and unspecified malignant neoplasm of lymph node, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 820, 821, 822, 823, 824, 825, 840, 841, 842, with relative weights from 1.0104 to 5.8648 depending on complications. Higher weights mean higher Medicare reimbursement.
Is C77.9 a CC or MCC?
CMS lists C77.9 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 24 closely related codes in its exclusion list.
What is the ICD-9 equivalent of C77.9?
Under the General Equivalence Mappings, secondary and unspecified malignant neoplasm of lymph node, unspecified converts to ICD-9-CM 196.9 (mal neo lymph node NOS). The mapping is a direct match.
What HCC is C77.9?
C77.9 (secondary and unspecified malignant neoplasm of lymph node, unspecified) maps to CMS-HCC Category 18 (Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid), commonly written as HCC 18, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 10 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 20.
Does C77.9 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, C77.9 adds a risk adjustment factor of about 2.341 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 1.110 to 2.537 depending on the payment segment). A more severe related category (HCC 17) supersedes it when both are reported. See the full factor table on the HCC 18 category page.
