C91.12 maps to CMS-HCC V28 22. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools

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 lookupC91.12

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)

C91.12

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

Chronic lymphocytic leukemia of B-cell type in relapse

A type of blood cancer (chronic lymphocytic leukemia) that started in B-cells and has returned after initial treatment.

Buddy Insight

Chronic lymphocytic leukemia of B-cell type in relapse indicates that a previously treated and remission-achieving CLL has returned with detectable disease activity.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 22

Bladder, Colorectal, and Othe...

Coefficient HCC 22: 0.363 (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 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 19

Leukemias and Other Hematolog...

Code-level coefficient reference

Code Book Path

Official

C91Lymphoid leukemia C91.1Chronic lymphocytic leukemia of B-cell type C91.12Chronic lymphocytic leukemia of B-cell type in relapse

Inclusion Terms

Official

Lymphoplasmacytic leukemiaInherited from C91.1
Richter syndromeInherited from C91.1

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

C91.10Chronic lymphocytic leukemia of B-cell type not having achieved remission C91.11Chronic lymphocytic leukemia of B-cell type in remission

Includes

Official

No Includes notes are included in this display for C91.12. Check the code and parent instructions in the Code Book.

Excludes 1

Official

personal history of leukemia (Z85.6)Inherited from C91, C91.1
lymphoplasmacytic lymphoma (C83.0-)Inherited from C91, C91.1

Code First

Official

No Code First sequencing instructions are included in this display for C91.12. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for C91.12. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for C91.12. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Documentation must confirm both a prior period of remission and current evidence of disease recurrence, including rising lymphocyte counts, progressive lymphadenopathy, or bone marrow re-infiltration.

The date of relapse, interval since last remission, and prior treatment regimens should be documented.

Updated cytogenetic and molecular testing (including TP53 mutation and del(17p) status) should be noted.

MEAT Support

HCC Buddy guidance

The date of relapse, interval since last remission, and prior treatment regimens should be documented.

Updated cytogenetic and molecular testing (including TP53 mutation and del(17p) status) should be noted.

Audit Caution

HCC Buddy guidance

Relapse requires documented prior remission followed by recurrence -

do not use this code for progressive disease that never responded to treatment (that is C91.10). Ensure the provider explicitly states relapse rather than assuming it from a treatment change. The distinction between relapse and refractory disease has important clinical and coding implications.

Common Mistakes

HCC Buddy guidance

C91.10 (B-CLL not in remission) is used for active disease that never achieved remission or for initial diagnosis. C91.11 (B-CLL in remission) applies when disease is controlled. Refractory CLL (disease progressing during treatment without ever achieving remission) should be coded as C91.10, not C91.

C91.Z2 (other lymphoid leukemia in relapse) is a less specific alternative.

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 C91.12 an HCC code?

Yes. C91.12 (Chronic lymphocytic leukemia of B-cell type in relapse) maps to HCC 22, Bladder, Colorectal, and Other Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.363. 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: C91.12 is billable and maps to V28 HCC 22, Bladder, Colorectal, and Other Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C91.12
Description: Chronic lymphocytic leukemia of B-cell type in relapse
HCC (V28): HCC 22 — Bladder, Colorectal, and Other Cancers
RAF reference coefficient: 0.363
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 22, Bladder, Colorectal, and Other Cancers

0.363

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 C91.12 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C91.12

For C91.12, 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

C91.12 is the ICD-10-CM diagnosis code for chronic lymphocytic leukemia of b-cell type in relapse. A type of blood cancer (chronic lymphocytic leukemia) that started in B-cells and has returned after initial treatment. C91.12 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, C91.12 maps to Bladder, Colorectal, and Other Cancers (HCC 22) with a source-labeled community, non-dual, aged reference coefficient of 0.363. 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.

The fifth character '2' indicates relapse status - ensure documentation clearly states the cancer has returned after remission. For C91.12, 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 C91.12 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•The fifth character '2' indicates relapse status - ensure documentation clearly states the cancer has returned after remission
•This code is specific to B-cell type CLL; verify cell type is documented before coding

Clinical Significance

Chronic lymphocytic leukemia of B-cell type in relapse indicates that a previously treated and remission-achieving CLL has returned with detectable disease activity. Relapsed CLL often requires a change in treatment strategy and may indicate development of resistance to prior therapy. Relapsed disease frequently behaves more aggressively and may carry adverse cytogenetic changes acquired during treatment.

Documentation Requirements

✓Documentation must confirm both a prior period of remission and current evidence of disease recurrence, including rising lymphocyte counts, progressive lymphadenopathy, or bone marrow re-infiltration.
✓The date of relapse, interval since last remission, and prior treatment regimens should be documented.
✓Updated cytogenetic and molecular testing (including TP53 mutation and del(17p) status) should be noted.

Commonly Confused Codes

•C91.10 (B-CLL not in remission) is used for active disease that never achieved remission or for initial diagnosis. C91.11 (B-CLL in remission) applies when disease is controlled. Refractory CLL (disease progressing during treatment without ever achieving remission) should be coded as C91.10, not C91.
•C91.Z2 (other lymphoid leukemia in relapse) is a less specific alternative.