C91.62
BillableProlymphocytic leukemia of T-cell type, in relapse
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C91.62 an HCC code?
Yes. C91.62 maps to Lymphoma and Other 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 C91.62
For C91.62 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 C91.62 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C91.62 is the ICD-10-CM diagnosis code for prolymphocytic leukemia of t-cell type, in relapse. A rare blood cancer (prolymphocytic leukemia) affecting T-cells that has returned after a period of remission. C91.62 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, C91.62 maps to Lymphoma and Other Cancers (HCC 19) with a community, non-dual, aged base RAF weight of 0.105. Under the older V24 model, C91.62 mapped to the same category but with a base RAF weight of 0.675 — V28 recalibrated weights across the entire model. 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.
The fifth character '2' indicates relapse - document that cancer has recurred after remission. Because C91.62 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 C91.62 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 - document that cancer has recurred after remission
- •T-cell prolymphocytic leukemia has different prognosis than B-cell type; ensure correct subtype coding
Clinical Significance
T-cell prolymphocytic leukemia in relapse indicates recurrence after prior remission, which is unfortunately the expected course for most T-PLL patients. Relapsed T-PLL is extremely difficult to treat, with very limited effective salvage options and a dismal prognosis. Re-treatment with alemtuzumab may achieve second remissions but duration is typically shorter, and allogeneic transplant in relapse has poor outcomes.
Documentation Requirements
- ✓Documentation must confirm prior remission and evidence of disease recurrence, including rising lymphocyte counts with prolymphocytic morphology, recurrent organomegaly, or skin involvement.
- ✓Duration of prior remission, previous treatment regimens, and response to re-treatment should be documented.
- ✓Updated cytogenetic and molecular studies at relapse help guide salvage therapy selection.