C79.2
BillableSecondary malignant neoplasm of skin
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C79.2 an HCC code?
Yes. C79.2 maps to Metastatic Cancer to Peritoneum and Other Specified Sites 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 C79.2
For C79.2 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 C79.2 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C79.2 is the ICD-10-CM diagnosis code for secondary malignant neoplasm of skin. Cancer that has spread to the skin from a primary cancer in another part of the body. C79.2 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, C79.2 maps to Metastatic Cancer to Peritoneum and Other Specified Sites (HCC 18) with a community, non-dual, aged base RAF weight of 0.368. Under the older CMS-HCC V24 model, C79.2 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.
Document the specific anatomical location of the skin lesion if possible, as this may affect treatment planning and prognosis. Because C79.2 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 C79.2 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the specific anatomical location of the skin lesion if possible, as this may affect treatment planning and prognosis
- •Ensure the primary cancer site is coded separately to provide complete clinical picture of metastatic disease
Clinical Significance
Secondary malignant neoplasm of skin indicates metastatic cancer has spread to the skin from an internal primary cancer. Cutaneous metastases are relatively uncommon but carry significant prognostic implications, often indicating widely disseminated disease. The most common primary cancers that metastasize to skin include breast, lung, colorectal, and melanoma.
Documentation Requirements
- ✓Primary cancer site documented and coded separately
- ✓Anatomical location of the cutaneous metastasis
- ✓Biopsy confirmation distinguishing metastatic deposits from primary skin cancers
- ✓Number and distribution of skin lesions
- ✓Clinical description — nodular, inflammatory, or ulcerating presentation
Excludes 1 — Do NOT code together
- secondary Merkel cell carcinoma (C7B.1)
Commonly Confused Codes
- •C43.0-C43.9 — Primary malignant melanoma of skin; melanoma is a primary skin cancer, not metastatic from another site
- •C44.0-C44.99 — Other primary malignant neoplasms of skin; basal cell and squamous cell carcinomas are primary, not secondary
- •C79.89 — Secondary malignant neoplasm of other specified sites; skin metastases have their own specific code C79.2
- •D03.0-D03.9 — Melanoma in situ; this is a pre-invasive primary lesion, not metastatic disease