C84.11
BillableSézary disease, lymph nodes of head, face, and neck
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C84.11 an HCC code?
Yes. C84.11 maps to Metastatic Cancer and Acute Leukemia 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 C84.11
For C84.11 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 C84.11 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C84.11 is the ICD-10-CM diagnosis code for sézary disease, lymph nodes of head, face, and neck. Sézary disease, an aggressive form of skin cancer, affecting lymph nodes in the head, face, and neck region. C84.11 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of lymphoid, hematopoietic and related tissue (c81-c96).
Under the CMS-HCC V28 risk adjustment model, C84.11 maps to Metastatic Cancer and Acute Leukemia (HCC 17) with a community, non-dual, aged base RAF weight of 0.368. Under the older CMS-HCC V24 model, C84.11 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.
Verify documentation specifies head, face, and/or neck lymph node involvement. Because C84.11 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 C84.11 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify documentation specifies head, face, and/or neck lymph node involvement
- •This is a site-specific code; use only when lymph nodes in this region are confirmed affected
Clinical Significance
Sezary disease involving head, face, and neck lymph nodes indicates lymph node involvement in this aggressive leukemic T-cell lymphoma. Cervical and facial lymphadenopathy is common in Sezary disease due to the generalized nature of the disease. Lymph node involvement is expected in Sezary disease staging and contributes to the overall disease burden assessment.
Documentation Requirements
- ✓Peripheral blood demonstrating circulating Sezary cells
- ✓Head/face/neck lymph node involvement confirmed by imaging or biopsy
- ✓Skin biopsy confirming cutaneous T-cell lymphoma
- ✓TNMB staging reflecting nodal involvement
- ✓Treatment plan for advanced cutaneous T-cell lymphoma