C84.49
BillablePeripheral T-cell lymphoma, not elsewhere classified, extranodal and solid organ sites
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C84.49 an HCC code?
Yes. C84.49 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 C84.49
For C84.49 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 C84.49 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C84.49 is the ICD-10-CM diagnosis code for peripheral t-cell lymphoma, not elsewhere classified, extranodal and solid organ sites. A type of cancer affecting T-cells that is not classified elsewhere, involving organs outside the lymph node system or solid organs. C84.49 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, C84.49 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, C84.49 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.
Identify and document the specific extranodal or solid organ sites involved. Because C84.49 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 C84.49 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Identify and document the specific extranodal or solid organ sites involved
- •Distinguish between nodal and extranodal involvement for accurate coding
Clinical Significance
Peripheral T-cell lymphoma not elsewhere classified involving extranodal and solid organ sites signifies disease occurring outside of the lymph node system, such as in the liver, lungs, bone, gastrointestinal tract, or skin. Extranodal involvement often indicates advanced disease and may require additional diagnostic workup. This code is important for distinguishing organ-based disease from purely nodal presentations.
Documentation Requirements
- ✓Pathology confirming PTCL-NOS in extranodal tissue with T-cell immunophenotype
- ✓Identification of the specific organ or extranodal site involved
- ✓Biopsy of the extranodal site confirming lymphoma rather than reactive changes
- ✓Imaging documenting the extent of extranodal disease
- ✓Exclusion of more specific extranodal T-cell lymphoma subtypes (enteropathy-associated, hepatosplenic, subcutaneous panniculitis-like)