C82.42
BillableFollicular lymphoma grade IIIb, intrathoracic lymph nodes
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C82.42 an HCC code?
Yes. C82.42 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors 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 C82.42
For C82.42 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 C82.42 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C82.42 is the ICD-10-CM diagnosis code for follicular lymphoma grade iiib, intrathoracic lymph nodes. A type of cancer of the lymph system (follicular lymphoma) that is grade IIIb and located in the lymph nodes within the chest cavity. C82.42 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, C82.42 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors (HCC 21) with a community, non-dual, aged base RAF weight of 0.545. Under the older CMS-HCC V24 model, C82.42 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.
Intrathoracic lymph nodes are located in the chest; confirm imaging or pathology documentation supports this location. Because C82.42 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 C82.42 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Intrathoracic lymph nodes are located in the chest; confirm imaging or pathology documentation supports this location
- •Chest involvement may affect respiratory function; note any clinical symptoms in the medical record
Clinical Significance
Follicular lymphoma grade IIIb in intrathoracic lymph nodes combines the most aggressive follicular subtype with mediastinal or hilar disease. This presentation may require urgent treatment for bulky mediastinal disease with compressive symptoms. Grade IIIb is managed with curative-intent regimens similar to DLBCL, making prompt and accurate coding essential for treatment pathway determination.
Documentation Requirements
- ✓Pathology confirming grade IIIb pattern
- ✓CT/PET documenting intrathoracic node involvement with size measurements
- ✓Assessment for bulky mediastinal disease and compressive symptoms
- ✓Expert hematopathology review distinguishing from DLBCL and primary mediastinal B-cell lymphoma
- ✓Urgent treatment plan if symptomatic
Commonly Confused Codes
- •C82.32 — Grade IIIa, intrathoracic; IIIa has centrocytes, IIIb does not
- •C82.22 — Grade III unspecified, intrathoracic; use C82.42 when IIIb is confirmed
- •C85.22 — Mediastinal large B-cell lymphoma; a distinct entity with different biology
- •C83.32 — DLBCL, intrathoracic; if pathology review reclassifies