C91.A1
BillableMature B-cell leukemia Burkitt-type, in remission
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C91.A1 an HCC code?
Yes. C91.A1 maps to Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model (and Lymphoma and Other Cancers under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. 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.
MEAT Criteria for C91.A1
For C91.A1 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.A1 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C91.A1 is the ICD-10-CM diagnosis code for mature b-cell leukemia burkitt-type, in remission. A specific aggressive type of B-cell blood cancer (Burkitt-type) that is currently in remission. C91.A1 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.A1 maps to Lung and Other Severe Cancers (HCC 20) with a community, non-dual, aged base RAF weight of 0.000. Under the older CMS-HCC V24 model, C91.A1 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.
This code is more specific than C91.90-92 and requires documentation confirming Burkitt-type morphology. Because C91.A1 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.A1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code is more specific than C91.90-92 and requires documentation confirming Burkitt-type morphology
- •Verify pathology or hematology reports confirm the Burkitt-type classification before coding
Clinical Significance
Mature B-cell leukemia Burkitt-type in remission indicates that this extremely aggressive leukemia has responded to intensive chemotherapy. Burkitt leukemia is one of the most curable aggressive hematologic malignancies when treated promptly with appropriate regimens, with cure rates exceeding 70-80% in many series. Remission typically requires documentation of bone marrow recovery with no detectable Burkitt cells.
Documentation Requirements
- ✓Provider must explicitly state remission status with supporting evidence including bone marrow biopsy showing no residual disease, normalized blood counts, and resolution of any extramedullary involvement.
- ✓Central nervous system clearance should be documented if CNS disease was present.
- ✓The intensive chemotherapy regimen used and date of remission achievement must be recorded.
- ✓MRD assessment results should be included when available.
Commonly Confused Codes
- •C91.A0 (Burkitt leukemia not in remission) is for active disease.
- •C91.A2 (Burkitt leukemia in relapse) is for recurrent disease.
- •C83.71 (Burkitt lymphoma in remission) is for the lymphoma variant.
- •C91.01 (acute lymphoblastic leukemia in remission) is less specific and should not be used when Burkitt-type is confirmed.