C81.20
BillableMixed cellularity Hodgkin lymphoma, unspecified site
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C81.20 an HCC code?
Yes. C81.20 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 C81.20
For C81.20 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 C81.20 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C81.20 is the ICD-10-CM diagnosis code for mixed cellularity hodgkin lymphoma, unspecified site. A type of Hodgkin lymphoma with mixed cellularity pattern (containing various cell types) at an unspecified location. C81.20 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, C81.20 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, C81.20 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 only when the specific lymph node site is not documented; attempt to obtain site information for more specific coding. Because C81.20 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 C81.20 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when the specific lymph node site is not documented; attempt to obtain site information for more specific coding
- •Requires seventh character for encounter type and remission status
Clinical Significance
Mixed cellularity Hodgkin lymphoma at an unspecified site is the second most common subtype of classic Hodgkin lymphoma, accounting for approximately 20-25% of cases. It is more common in older adults, males, and immunocompromised patients (particularly HIV-positive individuals) compared to nodular sclerosis. Mixed cellularity features a heterogeneous cellular background with classic Reed-Sternberg cells and is frequently associated with Epstein-Barr virus infection.
Documentation Requirements
- ✓Pathology report confirming mixed cellularity subtype with Reed-Sternberg cells
- ✓Immunohistochemistry (CD15+, CD30+, EBV status)
- ✓HIV testing status if not previously documented
- ✓Query provider for specific lymph node site to enable a more specific code
- ✓Ann Arbor staging including B-symptoms assessment
- ✓Treatment plan (ABVD or equivalent regimen)
Commonly Confused Codes
- •C81.10 — Nodular sclerosis Hodgkin lymphoma: Most common subtype; requires pathology to distinguish from mixed cellularity
- •C81.21-C81.29 — Site-specific mixed cellularity codes: Use these when the lymph node location is documented
- •C81.00 — NLPHL: Completely different subtype with different immunophenotype
- •C81.40 — Lymphocyte-rich Hodgkin lymphoma: Less common subtype; pathology differentiates