What is ICD-10 code C84.41?

C84.41 is the ICD-10-CM diagnosis code for Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of head, face, and neck. A type of T-cell lymphoma affecting the lymph nodes in the head, face, and neck region. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C84.41 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C84.41 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. C84.41 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. C84.41 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does C84.41 map to under V28?

C84.41 maps to CMS-HCC V28 HCC 19 (Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM C84.41: Peripheral T-cell lymphoma

C84.41 maps to CMS-HCC V28 19. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · HCC coding software

ICD-10-CM Code View

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Code lookupC84.41Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

C84.41

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

Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of head, face, and neck

A type of T-cell lymphoma affecting the lymph nodes in the head, face, and neck region.

Buddy Insight

CMS-HCC V28

Mapped

HCC 19

Myelodysplastic Syndromes, Mu...

Code-level coefficient reference

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 010

HHS-HCC 010 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

C84Mature T/NK-cell lymphomas

C84.4Peripheral T-cell lymphoma, not elsewhere classified

C84.41Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of head, face, and neck

Inclusion Terms

Official

Lennert's lymphoma
Lymphoepithelioid lymphoma
Mature T-cell lymphoma, not elsewhere classified

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C84.41 in this effective period.

Related Child Codes

Official

C84.40Peripheral T-cell lymphoma, not elsewhere classified, unspecified site

C84.42Peripheral T-cell lymphoma, not elsewhere classified, intrathoracic lymph nodes

C84.43Peripheral T-cell lymphoma, not elsewhere classified, intra-abdominal lymph nodes

C84.44Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of axilla and upper limb

C84.45Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of inguinal region and lower limb

Includes

Official

ICD-10-CM does not list Includes notes for C84.41 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for C84.41 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C84.41 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C84.41 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C84.41 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Pathology confirming peripheral T-cell lymphoma with T-cell markers on immunohistochemistry

Documentation confirming head, face, or neck lymph node involvement

Imaging (CT or PET/CT) of the head and neck region

Staging documentation

MEAT Support

HCC Buddy guidance

Pathology confirming peripheral T-cell lymphoma with T-cell markers on immunohistochemistry

Documentation confirming head, face, or neck lymph node involvement

Imaging (CT or PET/CT) of the head and neck region

Staging documentation

Audit Caution

HCC Buddy guidance

Defaulting to unspecified site when head/face/neck lymph node involvement is clearly documented

Confusing peripheral T-cell lymphoma with cutaneous T-cell lymphoma presenting in the head/neck area

Not verifying T-cell lineage through immunohistochemistry — B-cell and T-cell lymphomas require different treatment

Using head and neck carcinoma codes instead of lymphoma codes when the disease originates in lymph nodes

Common Mistakes

HCC Buddy guidance

C84.01 — Mycosis fungoides, head/face/neck: Cutaneous T-cell lymphoma distinct from peripheral T-cell lymphoma

C84.11 — Sezary disease, head/face/neck: Leukemic cutaneous T-cell lymphoma, different entity

C83.91 — Non-follicular lymphoma, unspecified, head/face/neck: B-cell or unspecified lineage; verify T-cell markers

C84.40 — Peripheral T-cell lymphoma, unspecified site: Use C84.41 when head/face/neck involvement is confirmed

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 C84.41 an HCC code?

Yes. C84.41 (Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of head, face, and neck) maps to HCC 19, Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 1.798. 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: C84.41 is billable and maps to V28 HCC 19, Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C84.41
Description: Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of head, face, and neck
HCC (V28): HCC 19 — Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers
RAF reference coefficient: 1.798
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 19, Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers

1.798

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 C84.41 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for C84.41

For C84.41 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 C84.41 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

C84.41 is the ICD-10-CM diagnosis code for peripheral t-cell lymphoma, not elsewhere classified, lymph nodes of head, face, and neck. A type of T-cell lymphoma affecting the lymph nodes in the head, face, and neck region. C84.41 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, C84.41 maps to Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers (HCC 19) with a source-labeled community, non-dual, aged reference coefficient of 1.798. No V24 mapping is shown for C84.41; use the applicable model and payment year when reviewing the V28 mapping. 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. 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.

Confirm documentation specifies involvement of head, face, or neck lymph nodes. Because C84.41 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. 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 C84.41 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Confirm documentation specifies involvement of head, face, or neck lymph nodes
•This code is site-specific; do not use if involvement is in other lymph node regions

Clinical Significance

Peripheral T-cell lymphoma, not elsewhere classified, involving lymph nodes of the head, face, and neck indicates this aggressive T-cell malignancy has been localized to cervical, preauricular, or other head/neck lymph nodes. Site-specific coding supports accurate staging and treatment planning. Head and neck presentations may be detected earlier due to visible or palpable lymphadenopathy, potentially allowing for earlier intervention.

Documentation Requirements

✓Pathology confirming peripheral T-cell lymphoma with T-cell markers on immunohistochemistry
✓Documentation confirming head, face, or neck lymph node involvement
✓Imaging (CT or PET/CT) of the head and neck region
✓Staging documentation
✓Treatment plan — systemic therapy typically required even for localized disease

Commonly Confused Codes

•C84.01: Mycosis fungoides, head/face/neck: Cutaneous T-cell lymphoma distinct from peripheral T-cell lymphoma
•C84.11: Sezary disease, head/face/neck: Leukemic cutaneous T-cell lymphoma, different entity
•C83.91: Non-follicular lymphoma, unspecified, head/face/neck: B-cell or unspecified lineage; verify T-cell markers
•C84.40: Peripheral T-cell lymphoma, unspecified site: Use C84.41 when head/face/neck involvement is confirmed