C91.01 ICD-10-CM Code: Acute lymphoblastic leukemia, in remission
C91.01 maps to CMS-HCC V28 18. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software
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FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of lymphoid, hematopoietic and related tissue (C81-C96)
C91.01
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceAcute lymphoblastic leukemia, in remission
A fast-growing blood cancer affecting young white blood cells that is currently in remission with no detectable disease.
Buddy Insight
Acute lymphoblastic leukemia in remission indicates successful induction chemotherapy with clearance of blast cells from the bone marrow (typically less than 5% blasts).
CMS-HCC V28
MappedHCC 18
Coefficient HCC 18: 2.341 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
Context neededHCC 008, HCC 009
Coefficient needs member context
ESRD/PACE
Context neededHCC 8
Coefficient needs member context
RXHCC
MappedHCC 19
Code-level coefficient reference
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for C91.01. 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 C91.01. Check the code and parent instructions in the Code Book.
Excludes 1
Official- personal history of leukemia (Z85.6)Inherited from C91
Code First
OfficialNo Code First sequencing instructions are included in this display for C91.01. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for C91.01. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for C91.01. 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 C91.01 an HCC code?
Yes. C91.01 (Acute lymphoblastic leukemia, in remission) maps to HCC 18, Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 2.341. 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: C91.01 is billable and maps to V28 HCC 18, Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- C91.01
- Description
- Acute lymphoblastic leukemia, in remission
- HCC (V28)
- HCC 18 — Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid
- RAF reference coefficient
- 2.341
- 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 C91.01 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for C91.01
For C91.01, 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
C91.01 is the ICD-10-CM diagnosis code for acute lymphoblastic leukemia, in remission. A fast-growing blood cancer affecting young white blood cells that is currently in remission with no detectable disease. C91.01 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, C91.01 maps to Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid (HCC 18) with a source-labeled community, non-dual, aged reference coefficient of 2.341. No V24 mapping is shown for C91.01; 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.
Remission requires explicit physician documentation and typically supported by lab values and bone marrow findings. For C91.01, 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 C91.01 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Remission requires explicit physician documentation and typically supported by lab values and bone marrow findings
- •This code indicates successful treatment response; document the date remission was achieved if available
Clinical Significance
Acute lymphoblastic leukemia in remission indicates successful induction chemotherapy with clearance of blast cells from the bone marrow (typically less than 5% blasts). Remission is a critical milestone but does not constitute cure, as patients require prolonged consolidation and maintenance therapy lasting 2-3 years to prevent relapse. Minimal residual disease monitoring is increasingly used to guide treatment intensity.
Documentation Requirements
- ✓Provider must document remission with supporting bone marrow biopsy showing less than 5% blasts, normalization of blood counts, and resolution of extramedullary disease.
- ✓Minimal residual disease status, current treatment phase (consolidation, maintenance), ongoing cerebrospinal fluid monitoring, and treatment protocol must be recorded.
Commonly Confused Codes
- •C91.00 (ALL not in remission) indicates active disease.
- •C91.02 (ALL in relapse) indicates recurrence after remission.
- •Z85.6 (personal history of leukemia) is only appropriate when treatment is complete and the disease is considered cured.
- •C91.10 (chronic lymphocytic leukemia) is an entirely different entity.