C81.20 maps to CMS-HCC V28 21. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupC81.20

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of lymphoid, hematopoietic and related tissue (C81-C96)

C81.20

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Mixed cellularity Hodgkin lymphoma, unspecified site

A type of Hodgkin lymphoma with mixed cellularity pattern (containing various cell types) at an unspecified location.

Buddy Insight

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.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 21

Lymphoma and Other Cancers

Coefficient HCC 21: 0.671 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 012

HHS-HCC 012 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 10

Lymphoma and Other Cancers

Code-level coefficient reference

RXHCC

Mapped

HCC 21

Lymphomas and Other Hematolog...

Code-level coefficient reference

Code Book Path

Official

C81Hodgkin lymphoma C81.2Mixed cellularity Hodgkin lymphoma C81.20Mixed cellularity Hodgkin lymphoma, unspecified site

Inclusion Terms

Official

Mixed cellularity classical Hodgkin lymphomaInherited from C81.2

Excludes 2

Official

Kaposi's sarcoma of lymph nodes (C46.3)Inherited from C81-C96
secondary and unspecified neoplasm of lymph nodes (C77.-)Inherited from C81-C96
secondary neoplasm of bone marrow (C79.52)Inherited from C81-C96
secondary neoplasm of spleen (C78.89)Inherited from C81-C96

Related Codes

Official

C81.21Mixed cellularity Hodgkin lymphoma, lymph nodes of head, face, and neck C81.22Mixed cellularity Hodgkin lymphoma, intrathoracic lymph nodes C81.23Mixed cellularity Hodgkin lymphoma, intra-abdominal lymph nodes C81.24Mixed cellularity Hodgkin lymphoma, lymph nodes of axilla and upper limb C81.25Mixed cellularity Hodgkin lymphoma, lymph nodes of inguinal region and lower limb

Includes

Official

No Includes notes are included in this display for C81.20. Check the code and parent instructions in the Code Book.

Excludes 1

Official

personal history of Hodgkin lymphoma (Z85.71)Inherited from C81

Code First

Official

No Code First sequencing instructions are included in this display for C81.20. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for C81.20. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for C81.20. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

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

MEAT Support

HCC Buddy guidance

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

Audit Caution

HCC Buddy guidance

Using unspecified site when lymph node location is available in imaging or clinical notes

Confusing mixed cellularity with other Hodgkin lymphoma subtypes — pathology is the arbiter

Not testing for HIV in patients with mixed cellularity Hodgkin lymphoma, given the association

Missing EBV association documentation, which has prognostic implications

Common Mistakes

HCC Buddy guidance

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

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is C81.20 an HCC code?

Yes. C81.20 (Mixed cellularity Hodgkin lymphoma, unspecified site) maps to HCC 21, Lymphoma and Other Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.671. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: C81.20 is billable and maps to V28 HCC 21, Lymphoma and Other Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C81.20
Description: Mixed cellularity Hodgkin lymphoma, unspecified site
HCC (V28): HCC 21 — Lymphoma and Other Cancers
RAF reference coefficient: 0.671
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 21, Lymphoma and Other Cancers

0.671

ESRDHCC 10, Lymphoma and Other Cancers

Not separately weighted

RxHCCHCC 21, Lymphomas and Other Hematologic Cancers

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work C81.20 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C81.20

For C81.20, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

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

Coder workflow notes

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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 Lymphoma and Other Cancers (HCC 21) with a source-labeled community, non-dual, aged reference coefficient of 0.671. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Use this code only when the specific lymph node site is not documented; attempt to obtain site information for more specific coding. For C81.20, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, 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