C85.22
BillableMediastinal (thymic) large B-cell lymphoma, intrathoracic lymph nodes
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C85.22 an HCC code?
Yes. C85.22 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 C85.22
For C85.22 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 C85.22 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C85.22 is the ICD-10-CM diagnosis code for mediastinal (thymic) large b-cell lymphoma, intrathoracic lymph nodes. This is a type of cancer that starts in large B-cells (a type of white blood cell) in the mediastinum (the space in the chest between the lungs) and has spread to the lymph nodes inside the chest. It is an aggressive form of lymphoma that typically affects young adults. C85.22 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, C85.22 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, C85.22 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.
Verify the documentation specifies 'mediastinal (thymic)' location and confirms involvement of intrathoracic lymph nodes to ensure accurate code selection. Because C85.22 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 C85.22 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify the documentation specifies 'mediastinal (thymic)' location and confirms involvement of intrathoracic lymph nodes to ensure accurate code selection
- •This code includes the site specification (intrathoracic lymph nodes); do not add additional codes for lymph node involvement unless documentation indicates extrathoracic sites are also affected
Clinical Significance
Mediastinal (thymic) large B-cell lymphoma involving intrathoracic lymph nodes is the most typical presentation, as this tumor originates from thymic B-cells in the anterior mediastinum. This aggressive lymphoma presents with a large mediastinal mass, often with superior vena cava syndrome, and predominantly affects young women aged 20-40. The intrathoracic location is clinically expected and this code accurately captures the primary site of disease.
Documentation Requirements
- ✓Pathology confirming primary mediastinal (thymic) large B-cell lymphoma with characteristic markers (CD20+, CD30+, CD23+, MAL protein+)
- ✓Chest imaging (CT or PET/CT) documenting intrathoracic lymph node or mediastinal mass involvement
- ✓Documentation of associated complications (superior vena cava syndrome, pleural effusion, pericardial effusion)
- ✓Staging workup and treatment plan