C83.91
BillableNon-follicular (diffuse) lymphoma, unspecified, 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 C83.91 an HCC code?
Yes. C83.91 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors 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 C83.91
For C83.91 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 C83.91 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C83.91 is the ICD-10-CM diagnosis code for non-follicular (diffuse) lymphoma, unspecified, lymph nodes of head, face, and neck. A type of blood cancer (non-follicular lymphoma) affecting the lymph nodes in the head, face, and neck region. C83.91 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, C83.91 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors (HCC 21) with a community, non-dual, aged base RAF weight of 0.545. Under the older CMS-HCC V24 model, C83.91 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.
Confirm involvement is limited to head, face, and neck lymph nodes. Because C83.91 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 C83.91 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Confirm involvement is limited to head, face, and neck lymph nodes
- •Document if disease is unilateral or bilateral for clinical staging purposes
Clinical Significance
Non-follicular (diffuse) lymphoma, unspecified type, of the head, face, and neck lymph nodes captures disease where the anatomic site is known but the specific non-follicular subtype has not been determined. Head and neck lymphadenopathy is often the initial presenting sign of lymphoma, making prompt biopsy and subtype identification important for treatment planning. This code should trigger a query for pathologic subtype clarification.
Documentation Requirements
- ✓Imaging or physical exam confirming head, face, or neck lymph node involvement
- ✓Pathology report — query for specific non-follicular subtype if not documented
- ✓Distinction between non-follicular lymphoma and other causes of cervical lymphadenopathy
- ✓Treatment plan and staging documentation
- ✓Disease status — active, in treatment, or surveillance