C84.45 ICD-10-CM Code: Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of inguinal region and lower limb
HCC Buddy Code Card
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FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of lymphoid, hematopoietic and related tissue (C81-C96)
C84.45
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidancePeripheral T-cell lymphoma, not elsewhere classified, lymph nodes of inguinal region and lower limb
A type of T-cell lymphoma affecting the lymph nodes in the groin and lower legs.
Buddy Insight
Peripheral T-cell lymphoma not elsewhere classified involving inguinal and lower limb lymph nodes is an aggressive lymphoma affecting the groin and lower extremity nodal basins.
CMS-HCC V28
MappedHCC 19
RAF 1.798
CMS-HCC V24
MappedHCC 10
RAF 0.675
ACA/HHS
MappedHCC 10
Varies by metal level
ESRD/PACE
MappedHCC 10
RAF 0.111
RXHCC
MappedHCC 21
RAF 0.410
Code Book Path
Inclusion Terms
Official- Lennert's lymphoma
- Lymphoepithelioid lymphoma
- Mature T-cell lymphoma, not elsewhere classified
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for C84.45 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for C84.45 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for C84.45 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for C84.45 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for C84.45 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for C84.45 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 C84.45 an HCC code?
Yes. C84.45 (Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of inguinal region and lower limb) maps to Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers under the CMS-HCC V28 risk adjustment model (and Lymphoma and Other Cancers under V24), with a community non-dual aged RAF of 1.798. It is billable for payment year 2026.
Coder answer: C84.45 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
- C84.45
- Description
- Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of inguinal region and lower limb
- HCC (V28)
- HCC 19 — Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers
- RAF
- 1.798
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
Each model's RAF is its CMS base weight for that model's standard population, so 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 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.
Work C84.45 in the Code Book — tabular path, V28 RAF, and MEAT checklist →
MEAT Criteria for C84.45
For C84.45 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 C84.45 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
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What This Code Means
C84.45 is the ICD-10-CM diagnosis code for peripheral t-cell lymphoma, not elsewhere classified, lymph nodes of inguinal region and lower limb. A type of T-cell lymphoma affecting the lymph nodes in the groin and lower legs. C84.45 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, C84.45 maps to Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers (HCC 19) with a community, non-dual, aged base RAF weight of 1.798. Under the older CMS-HCC V24 model, C84.45 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 documentation specifies inguinal region or lower limb lymph node involvement. Because C84.45 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 C84.45 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Confirm documentation specifies inguinal region or lower limb lymph node involvement
- •This includes lymph nodes of the hip, thigh, and lower extremity
Clinical Significance
Peripheral T-cell lymphoma not elsewhere classified involving inguinal and lower limb lymph nodes is an aggressive lymphoma affecting the groin and lower extremity nodal basins. This presentation may be associated with skin involvement on the lower extremities and must be carefully distinguished from cutaneous T-cell lymphoma subtypes. Site-specific coding reflects the distinct clinical presentation and potential complications.
Documentation Requirements
- ✓Pathology confirming PTCL-NOS with appropriate immunohistochemistry
- ✓Imaging or physical examination documenting inguinal and/or lower limb lymph node involvement
- ✓Documentation excluding other specific T-cell lymphoma subtypes
- ✓Clinical staging with notation of disease extent
- ✓Active disease status documented
Commonly Confused Codes
- •C84.65: Anaplastic large cell lymphoma, ALK-positive, inguinal/lower limb: Requires ALK positivity on pathology, a distinct entity with different prognosis
- •C84.75: Anaplastic large cell lymphoma, ALK-negative, inguinal/lower limb: Separate morphologic entity from PTCL-NOS
- •C84.A5: Cutaneous T-cell lymphoma, unspecified, inguinal/lower limb: Cutaneous T-cell lymphoma is a skin-primary disease (mycosis fungoides, Sezary syndrome) distinct from nodal PTCL-NOS
- •C84.48: PTCL-NOS, multiple sites: Use only when disease is confined to inguinal/lower limb region