C85.23
BillableMediastinal (thymic) large B-cell lymphoma, intra-abdominal lymph nodes
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C85.23 an HCC code?
Yes. C85.23 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 C85.23
For C85.23to 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 C85.23 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C85.23 is the ICD-10-CM diagnosis code for mediastinal (thymic) large b-cell lymphoma, intra-abdominal lymph nodes. A specific type of large B-cell lymphoma originating in the thymus gland with involvement of lymph nodes located inside the abdomen. C85.23 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, C85.23 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, C85.23 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.
Apply this code when mediastinal large B-cell lymphoma involves intra-abdominal lymph nodes such as mesenteric, retroperitoneal, or celiac nodes. Because C85.23 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 C85.23 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Apply this code when mediastinal large B-cell lymphoma involves intra-abdominal lymph nodes such as mesenteric, retroperitoneal, or celiac nodes
- •Ensure imaging or pathology documentation confirms intra-abdominal lymph node involvement
Clinical Significance
Mediastinal (thymic) large B-cell lymphoma involving intra-abdominal lymph nodes indicates disease that has spread beyond the primary mediastinal origin. This dissemination pattern affects prognosis and treatment approach, potentially requiring more aggressive regimens or radiation field modification. Extra-mediastinal spread occurs in a minority of cases and should be carefully documented for accurate staging.
Documentation Requirements
- ✓Original pathology confirming primary mediastinal (thymic) large B-cell lymphoma subtype with appropriate markers
- ✓Imaging or clinical confirmation of intra-abdominal lymph nodes involvement beyond the primary mediastinal mass
- ✓Documentation that this represents spread from primary mediastinal disease, not a de novo lymphoma at this site
- ✓Complete staging showing both primary mediastinal disease and secondary involvement
Commonly Confused Codes
- •C83.3x (Diffuse large B-cell lymphoma at same site) — PMBCL spreading to intra-abdominal lymph nodes should still be coded as C85.2x, not as DLBCL
- •C85.1x (Unspecified B-cell lymphoma at same site) — Use C85.2x when the mediastinal/thymic subtype is confirmed by pathology
- •C85.28 (PMBCL, lymph nodes of multiple sites) — Use site-specific code when a single secondary site is involved; use C85.28 for multiple sites