C77.3
BillableSecondary and unspecified malignant neoplasm of axilla and upper limb lymph nodes
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C77.3 an HCC code?
Yes. C77.3 maps to Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model (and Lymphoma and Other Cancers under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. 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.
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.
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 0.000. 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