What is ICD-10 code C91.11?

C91.11 is the ICD-10-CM diagnosis code for Chronic lymphocytic leukemia of B-cell type in remission. A slow-growing blood cancer of B-cells that is currently in remission with no detectable disease. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C91.11 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C91.11 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. C91.11 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. C91.11 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 C91.11 map to under V28?

C91.11 maps to CMS-HCC V28 22 (Bladder, Colorectal, and Other Cancers). The category number and label come from the CMS-HCC V28 model file for payment year 2026.

What does C91.11 pay in RAF?

C91.11 carries a community, non-dual, aged (CNA) RAF weight of 0.363 under CMS-HCC V28 for payment year 2026. The weight comes from the CMS V28 relative-factor file, not a hand-typed table.

What is the V28 vs V24 difference for C91.11?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For C91.11, V28 maps to Bladder, Colorectal, and Other Cancers at RAF 0.363 while V24 mapped to Lymphoma and Other Cancers at RAF 0.675. Both models can still appear in legacy data and in payer-specific lookback periods.

2026 ICD-10-CM C91.11: Chronic lymphocytic leukemia

C91.11 maps to CMS-HCC V28 22 (RAF 0.363). Documentation must support MEAT. MEAT criteria · RAF calculator · free HCC coding tools

ICD-10-CM Code View

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Code lookupC91.11Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

C91.11

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

Chronic lymphocytic leukemia of B-cell type in remission

A slow-growing blood cancer of B-cells that is currently in remission with no detectable disease.

Buddy Insight

CMS-HCC V28

Mapped

HCC 22

Bladder, Colorectal, and Othe...

RAF 0.363

CMS-HCC V24

Mapped

HCC 10

Lymphoma and Other Cancers

RAF 0.675

ACA/HHS

Mapped

HCC 10

HHS-HCC 10

Varies by metal level

ESRD/PACE

Mapped

HCC 10

Lymphoma and Other Cancers

RAF 0.111

RXHCC

Mapped

HCC 19

Lymphoma and Other Cancers

RAF 1.949

Code Book Path

Official

C91Lymphoid leukemia

C91.1Chronic lymphocytic leukemia of B-cell type

C91.11Chronic lymphocytic leukemia of B-cell type in remission

Inclusion Terms

Official

Lymphoplasmacytic leukemia
Richter syndrome

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C91.11 in this effective period.

Related Child Codes

Official

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

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

Includes

Official

ICD-10-CM does not list Includes notes for C91.11 in this effective period.

Excludes 1

Official

lymphoplasmacytic lymphoma (C83.0-)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C91.11 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C91.11 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C91.11 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

The provider must explicitly document remission status, ideally specifying partial versus complete remission per iwCLL criteria.

Documentation should include the date remission was achieved, the treatment regimen that induced remission, and the method of assessment (flow cytometry, imaging, bone marrow biopsy).

Ongoing monitoring plan and minimal residual disease (MRD) status should be noted when available.

MEAT Support

HCC Buddy guidance

The provider must explicitly document remission status, ideally specifying partial versus complete remission per iwCLL criteria.

Documentation should include the date remission was achieved, the treatment regimen that induced remission, and the method of assessment (flow cytometry, imaging, bone marrow biopsy).

Ongoing monitoring plan and minimal residual disease (MRD) status should be noted when available.

Audit Caution

HCC Buddy guidance

Do not assume remission based solely on stable lab values or lack of treatment -

the provider must explicitly state remission. Watch-and-wait patients who have never been treated are coded as C91.10, not C91.11, since remission implies prior treatment response. Do not confuse remission with cure; CLL patients in remission still carry the active diagnosis.

Common Mistakes

HCC Buddy guidance

C91.10 (B-CLL not in remission) applies when disease is active or remission has not been achieved.

C91.12 (B-CLL in relapse) is used when disease recurs after a documented remission.

Z85.6 (personal history of leukemia) should not be used while the patient still carries the CLL diagnosis, even in remission.

C91.91 (lymphoid leukemia, unspecified, in remission) is less specific.

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 C91.11 an HCC code?

Yes. C91.11 (Chronic lymphocytic leukemia of B-cell type in remission) maps to Bladder, Colorectal, 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 0.363. It is billable for payment year 2026.

Coder answer: C91.11 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: C91.11
Description: Chronic lymphocytic leukemia of B-cell type in remission
HCC (V28): HCC 22 — Bladder, Colorectal, and Other Cancers
RAF: 0.363
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 22, Bladder, Colorectal, and Other Cancers

0.363

V24HCC 10, Lymphoma and Other Cancers

0.675

ESRDHCC 10, Lymphoma and Other Cancers

0.111

RxHCCHCC 19, Lymphoma and Other Cancers

1.949

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 C91.11 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for C91.11

For C91.11 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 C91.11 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

C91.11 is the ICD-10-CM diagnosis code for chronic lymphocytic leukemia of b-cell type in remission. A slow-growing blood cancer of B-cells that is currently in remission with no detectable disease. C91.11 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, C91.11 maps to Bladder, Colorectal, and Other Cancers (HCC 22) with a community, non-dual, aged base RAF weight of 0.363. Under the older CMS-HCC V24 model, C91.11 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.

Remission in CLL must be documented by physician; may be partial or complete remission. Because C91.11 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 C91.11 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Remission in CLL must be documented by physician; may be partial or complete remission
•CLL can have long remission periods; document the date remission was achieved for continuity of care

Clinical Significance

Chronic lymphocytic leukemia of B-cell type in remission indicates that the patient's B-CLL has responded to treatment with no detectable disease activity, though the condition is considered incurable and requires ongoing surveillance. Remission in CLL may be partial (reduction in disease burden) or complete (no detectable disease by standard criteria), and the distinction should be documented. Patients in remission remain at risk for relapse and secondary malignancies.

Documentation Requirements

✓The provider must explicitly document remission status, ideally specifying partial versus complete remission per iwCLL criteria.
✓Documentation should include the date remission was achieved, the treatment regimen that induced remission, and the method of assessment (flow cytometry, imaging, bone marrow biopsy).
✓Ongoing monitoring plan and minimal residual disease (MRD) status should be noted when available.

Commonly Confused Codes

•C91.10 (B-CLL not in remission) applies when disease is active or remission has not been achieved.
•C91.12 (B-CLL in relapse) is used when disease recurs after a documented remission.
•Z85.6 (personal history of leukemia) should not be used while the patient still carries the CLL diagnosis, even in remission.
•C91.91 (lymphoid leukemia, unspecified, in remission) is less specific.