C84.16 ICD-10-CM Code: Sezary disease, intrapelvic lymph nodes
C84.16 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 · HCC Buddy coding tools
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FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of lymphoid, hematopoietic and related tissue (C81-C96)
C84.16
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceSezary disease, intrapelvic lymph nodes
Sézary disease, an aggressive form of skin cancer, affecting lymph nodes inside the pelvis.
Buddy Insight
Sezary disease with intrapelvic lymph node involvement indicates deep pelvic lymph node spread in this aggressive leukemic T-cell lymphoma.
CMS-HCC V28
MappedHCC 17
Coefficient HCC 17: 4.209 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 010
Code-level coefficient reference
ESRD/PACE
MappedHCC 10
Code-level coefficient reference
RXHCC
MappedHCC 19
Code-level coefficient reference
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for C84.16. 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
Includes
OfficialNo Includes notes are included in this display for C84.16. 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
OfficialNo Code First sequencing instructions are included in this display for C84.16. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for C84.16. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for C84.16. Check the code and parent instructions in the Code Book.
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 C84.16 an HCC code?
Yes. C84.16 (Sezary disease, intrapelvic lymph nodes) 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: C84.16 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
- C84.16
- Description
- Sezary disease, intrapelvic lymph nodes
- 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
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 C84.16 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for C84.16
For C84.16, 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
C84.16 is the ICD-10-CM diagnosis code for sezary disease, intrapelvic lymph nodes. Sézary disease, an aggressive form of skin cancer, affecting lymph nodes inside the pelvis. C84.16 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, C84.16 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. 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.
Confirm intrapelvic lymph node involvement through imaging or pathology reports. For C84.16, 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 C84.16 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Confirm intrapelvic lymph node involvement through imaging or pathology reports
- •This includes iliac, obturator, and other pelvic lymph nodes
Clinical Significance
Sezary disease with intrapelvic lymph node involvement indicates deep pelvic lymph node spread in this aggressive leukemic T-cell lymphoma. Intrapelvic involvement is relatively uncommon and represents significant visceral lymph node disease requiring systemic management. This finding typically contributes to advanced disease staging.
Documentation Requirements
- ✓Peripheral blood demonstrating circulating Sezary cells
- ✓Pelvic imaging documenting intrapelvic lymphadenopathy
- ✓Skin biopsy confirming cutaneous T-cell lymphoma
- ✓TNMB staging reflecting deep nodal disease
- ✓Systemic treatment plan