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C84.15 ICD-10-CM Code: Sezary disease, lymph nodes of inguinal region and lower limb

C84.15 maps to CMS-HCC V28 17. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · free HCC coding tools

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Code lookupC84.15

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

C84.15

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

Sezary disease, lymph nodes of inguinal region and lower limb

Sézary disease, an aggressive form of skin cancer, affecting lymph nodes in the groin and lower legs.

Buddy the Bee presenting code insight

Buddy Insight

Sezary disease with inguinal and lower limb lymph node involvement indicates lymph node spread in the groin and lower extremity regions of this aggressive leukemic T-cell lymphoma.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 17

Code-level coefficient reference

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 010

Code-level coefficient reference

ESRD/PACE

HCC 10

Code-level coefficient reference

RXHCC

HCC 19

Code-level coefficient reference

Code Book Path

Official
C84Mature T/NK-cell lymphomasC84.1Sezary diseaseC84.15Sezary disease, lymph nodes of inguinal region and lower limb

Inclusion Terms

Official

No inclusion terms are included in this display for C84.15. Check the code and parent instructions in the Code Book.

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
C84.10Sezary disease, unspecified siteC84.11Sezary disease, lymph nodes of head, face, and neckC84.12Sezary disease, intrathoracic lymph nodesC84.13Sezary disease, intra-abdominal lymph nodesC84.14Sezary disease, lymph nodes of axilla and upper limb

Includes

Official

No Includes notes are included in this display for C84.15. Check the code and parent instructions in the Code Book.

Excludes 1

Official
  • personal history of non-Hodgkin lymphoma (Z85.72)Inherited from C84

Code First

Official

No Code First sequencing instructions are included in this display for C84.15. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for C84.15. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for C84.15. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance
Peripheral blood demonstrating circulating Sezary cells
Inguinal or lower limb lymph node involvement confirmed by exam or imaging
Skin biopsy confirming cutaneous T-cell lymphoma
TNMB staging

MEAT Support

HCC Buddy guidance
Peripheral blood demonstrating circulating Sezary cells
Inguinal or lower limb lymph node involvement confirmed by exam or imaging
Skin biopsy confirming cutaneous T-cell lymphoma
TNMB staging

Audit Caution

HCC Buddy guidance
Confusing inguinal with intrapelvic lymph nodes — anatomically distinct with different codes
Using unspecified site when inguinal lymphadenopathy is clearly documented
Not distinguishing reactive inguinal lymphadenopathy from lymphomatous involvement
Missing Sezary cell documentation in blood work, leading to incorrect mycosis fungoides coding

Common Mistakes

HCC Buddy guidance
C84.05 — Mycosis fungoides, inguinal/lower limb: Distinct from Sezary disease; requires circulating malignant T-cells
C84.16 — Sezary disease, intrapelvic: Deep pelvic nodes are distinct from superficial inguinal nodes
C84.10 — Sezary disease, unspecified site: Use C84.15 when inguinal 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 C84.15 an HCC code?

Yes. C84.15 (Sezary disease, lymph nodes of inguinal region and lower limb) maps to HCC 17, Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 4.209. 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: C84.15 is billable and maps to V28 HCC 17, Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
C84.15
Description
Sezary disease, lymph nodes of inguinal region and lower limb
HCC (V28)
HCC 17 — Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic
RAF reference coefficient
4.209
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 17, Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic
4.209
ESRDHCC 10, Lymphoma and Other Cancers
Not separately weighted
RxHCCHCC 19, Leukemias 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 C84.15 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C84.15

For C84.15, 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

C84.15 is the ICD-10-CM diagnosis code for sezary disease, lymph nodes of inguinal region and lower limb. Sézary disease, an aggressive form of skin cancer, affecting lymph nodes in the groin and lower legs. C84.15 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, C84.15 maps to Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic (HCC 17) with a source-labeled community, non-dual, aged reference coefficient of 4.209. No V24 mapping is shown for C84.15; use the applicable model and payment year when reviewing the V28 mapping. 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.

Verify inguinal and/or lower limb lymph node involvement is documented. For C84.15, 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 C84.15 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Verify inguinal and/or lower limb lymph node involvement is documented
  • •This code includes both inguinal and lower extremity lymph nodes

Clinical Significance

Sezary disease with inguinal and lower limb lymph node involvement indicates lymph node spread in the groin and lower extremity regions of this aggressive leukemic T-cell lymphoma. Inguinal lymphadenopathy is common in Sezary disease, particularly when lower extremity skin involvement is prominent. This contributes to overall disease staging and treatment planning.

Documentation Requirements

  • ✓Peripheral blood demonstrating circulating Sezary cells
  • ✓Inguinal or lower limb lymph node involvement confirmed by exam or imaging
  • ✓Skin biopsy confirming cutaneous T-cell lymphoma
  • ✓TNMB staging
  • ✓Treatment plan for advanced-stage disease

Commonly Confused Codes

  • •C84.05: Mycosis fungoides, inguinal/lower limb: Distinct from Sezary disease; requires circulating malignant T-cells
  • •C84.16: Sezary disease, intrapelvic: Deep pelvic nodes are distinct from superficial inguinal nodes
  • •C84.10: Sezary disease, unspecified site: Use C84.15 when inguinal involvement is confirmed

Child Codes

C84.10Sezary disease, unspecified site
HCC 17
C84.11Sezary disease, lymph nodes of head, face, and neck
HCC 17
C84.12Sezary disease, intrathoracic lymph nodes
HCC 17
C84.13Sezary disease, intra-abdominal lymph nodes
HCC 17
C84.14Sezary disease, lymph nodes of axilla and upper limb
HCC 17
C84.15Sezary disease, lymph nodes of inguinal region and lower limb
HCC 17
C84.16Sezary disease, intrapelvic lymph nodes
HCC 17
C84.17Sezary disease, spleen
HCC 17
C84.18Sezary disease, lymph nodes of multiple sites
HCC 17
C84.19Sezary disease, extranodal and solid organ sites
HCC 17
C84.1ASezary disease, in remission
HCC 17

Code Hierarchy

└C84Mature T/NK-cell lymphomas└C84.1Sezary disease└C84.15Sezary disease, lymph nodes of inguinal region and lower limb
└C84.15Sezary disease, lymph nodes of inguinal region and lower limb

For C84.15, 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.

C84.15 maps to CMS-HCC V28 category 17, Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for C84.15. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

Work C84.15 in HCC Buddy

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