What is ICD-10 code C77.3?

C77.3 is the ICD-10-CM diagnosis code for Secondary and unspecified malignant neoplasm of axilla and upper limb lymph nodes. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C77.3 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C77.3 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. C77.3 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. C77.3 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for C77.3?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For C77.3, V28 maps to Lung and Other Severe Cancers at RAF 1.136 while V24 mapped to Lymphoma and Other Cancers at RAF 0.675. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting C77.3?

Use this code when documenting metastatic cancer to axillary or upper limb lymph nodes; always code the primary cancer site separately if known Distinguish between C77.3 (upper limb) and C77.4 (lower limb) based on anatomical location of affected lymph nodes Because C77.3 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

2026 ICD-10-CM C77.3: Secondary and unspecified

ICD-10-CM Code View

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Code lookupC77.3Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of ill-defined, other secondary and unspecified sites (C76-C80)

C77.3

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Secondary and unspecified malignant neoplasm of axilla and upper limb lymph nodes

Cancer that has spread to the lymph nodes in the armpit and upper arm area, either as a secondary spread from another cancer or when the primary source is unknown.

Buddy Insight

Secondary and unspecified malignant neoplasm of axillary and upper limb lymph nodes represents metastatic disease to the axillary or epitrochlear lymph nodes.

CMS-HCC V28

Mapped

HCC 20

Lung and Other Severe Cancers

RAF 1.136

CMS-HCC V24

Mapped

HCC 10

Lymphoma and Other Cancers

RAF 0.675

ACA/HHS

Mapped

HCC 8

HHS-HCC 8

Varies by metal level

ESRD/PACE

Mapped

HCC 10

Lymphoma and Other Cancers

RAF 0.111

RXHCC

Mapped

HCC 20

Cancer, Liver and Intrahepati...

RAF 0.491

Code Book Path

Official

C77Secondary and unspecified malignant neoplasm of lymph nodes

C77.3Secondary and unspecified malignant neoplasm of axilla and upper limb lymph nodes

Inclusion Terms

Official

Secondary and unspecified malignant neoplasm of pectoral lymph nodes

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C77.3 in this effective period.

Related Child Codes

Official

C77.0Secondary and unspecified malignant neoplasm of lymph nodes of head, face and neck

C77.1Secondary and unspecified malignant neoplasm of intrathoracic lymph nodes

C77.2Secondary and unspecified malignant neoplasm of intra-abdominal lymph nodes

C77.4Secondary and unspecified malignant neoplasm of inguinal and lower limb lymph nodes

C77.5Secondary and unspecified malignant neoplasm of intrapelvic lymph nodes

Includes

Official

ICD-10-CM does not list Includes notes for C77.3 in this effective period.

Excludes 1

Official

malignant neoplasm of lymph nodes, specified as primary (C81-C86, C88, C96.-)
mesentery metastasis of carcinoid tumor (C7B.04)
secondary carcinoid tumors of distant lymph nodes (C7B.01)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C77.3 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C77.3 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C77.3 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Pathology confirming malignant involvement of axillary or upper limb lymph nodes

Identification and coding of the primary malignancy (breast, melanoma, etc.)

Number of positive lymph nodes when available (important for breast cancer staging)

Laterality of lymph node involvement

MEAT Support

HCC Buddy guidance

Pathology confirming malignant involvement of axillary or upper limb lymph nodes

Identification and coding of the primary malignancy (breast, melanoma, etc.)

Number of positive lymph nodes when available (important for breast cancer staging)

Laterality of lymph node involvement

Audit Caution

HCC Buddy guidance

Coding axillary lymphoma as secondary malignant neoplasm — lymphomas are primary processes

Not coding the primary malignancy (especially breast cancer) alongside the lymph node code

Confusing reactive axillary lymphadenopathy with metastatic disease

Not documenting laterality of axillary nodal involvement

Common Mistakes

HCC Buddy guidance

C77.0 — Head, face, neck lymph nodes: Different lymph node region

C77.4 — Inguinal and lower limb lymph nodes: Lower extremity, not upper

C50.911-C50.919 — Breast cancer: Primary malignancy should be coded separately

C81-C86 — Lymphomas: Primary lymph node malignancy, not secondary

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is C77.3 an HCC code?

Yes. C77.3 (Secondary and unspecified malignant neoplasm of axilla and upper limb lymph nodes) maps to Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model (and Lymphoma and Other Cancers under V24), with a community non-dual aged RAF of 1.136. It is billable for payment year 2026.

Coder answer: C77.3 is billable and maps to V28 HCC 20, Lung and Other Severe Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C77.3
Description: Secondary and unspecified malignant neoplasm of axilla and upper limb lymph nodes
HCC (V28): HCC 20 — Lung and Other Severe Cancers
RAF: 1.136
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 20, Lung and Other Severe Cancers

1.136

V24HCC 10, Lymphoma and Other Cancers

0.675

ESRDHCC 10, Lymphoma and Other Cancers

0.111

RxHCCHCC 20, Cancer, Liver and Intrahepatic Bile Duct

0.491

Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

Work C77.3 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for C77.3

For C77.3 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed C77.3 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

C77.3 is the ICD-10-CM diagnosis code for secondary and unspecified malignant neoplasm of axilla and upper limb lymph nodes. Cancer that has spread to the lymph nodes in the armpit and upper arm area, either as a secondary spread from another cancer or when the primary source is unknown. C77.3 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of ill-defined, other secondary and unspecified sites (c76-c80).

Under the CMS-HCC V28 risk adjustment model, C77.3 maps to Lung and Other Severe Cancers (HCC 20) with a community, non-dual, aged base RAF weight of 1.136. Under the older CMS-HCC V24 model, C77.3 maps to Lymphoma and Other Cancers (HCC 10) with a community, non-dual, aged base RAF weight of 0.675. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Use this code when documenting metastatic cancer to axillary or upper limb lymph nodes; always code the primary cancer site separately if known. Because C77.3 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for C77.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Use this code when documenting metastatic cancer to axillary or upper limb lymph nodes; always code the primary cancer site separately if known
•Distinguish between C77.3 (upper limb) and C77.4 (lower limb) based on anatomical location of affected lymph nodes

Clinical Significance

Secondary and unspecified malignant neoplasm of axillary and upper limb lymph nodes represents metastatic disease to the axillary or epitrochlear lymph nodes. This is most commonly associated with breast cancer and melanoma metastasis. Axillary lymph node status is a critical staging factor in breast cancer and significantly impacts treatment decisions.

Documentation Requirements

✓Pathology confirming malignant involvement of axillary or upper limb lymph nodes
✓Identification and coding of the primary malignancy (breast, melanoma, etc.)
✓Number of positive lymph nodes when available (important for breast cancer staging)
✓Laterality of lymph node involvement
✓Imaging documenting extent of nodal disease

Commonly Confused Codes

•C77.0: Head, face, neck lymph nodes: Different lymph node region
•C77.4: Inguinal and lower limb lymph nodes: Lower extremity, not upper
•C50.911-C50.919: Breast cancer: Primary malignancy should be coded separately
•C81-C86: Lymphomas: Primary lymph node malignancy, not secondary
•C76.41/C76.42: Upper limb malignancy: Primary tumor of ill-defined site, not lymph node metastasis