C83.90
BillableNon-follicular (diffuse) lymphoma, unspecified, unspecified site
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C83.90 an HCC code?
Yes. C83.90 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 C83.90
For C83.90 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 C83.90 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C83.90 is the ICD-10-CM diagnosis code for non-follicular (diffuse) lymphoma, unspecified, unspecified site. A type of blood cancer (non-follicular lymphoma) where the specific location is not yet identified or documented. C83.90 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, C83.90 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, C83.90 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.
This is a less specific code; use only when site of involvement cannot be determined. Because C83.90 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 C83.90 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a less specific code; use only when site of involvement cannot be determined
- •Query provider if additional imaging or pathology results specify the lymphoma location
Clinical Significance
Non-follicular (diffuse) lymphoma, unspecified, at an unspecified site is the least specific code in the non-follicular lymphoma category, indicating both the subtype and anatomic site are unspecified. This code should prompt a query to the provider for more detailed pathology and imaging results. While it still maps to HCC categories, using more specific codes improves documentation quality and audit defensibility.
Documentation Requirements
- ✓Pathology report — query for specific non-follicular subtype if only 'lymphoma' or 'non-Hodgkin lymphoma' is documented
- ✓Any available imaging to determine site of involvement
- ✓Clinical notes supporting the lymphoma diagnosis
- ✓Treatment plan or referral to oncology
- ✓Disease status documentation
Commonly Confused Codes
- •C83.80 — Other non-follicular lymphoma, unspecified site: C83.80 indicates the subtype is known as 'other' but site is unspecified; C83.90 has both subtype and site unspecified
- •C85.90 — Non-Hodgkin lymphoma, unspecified, unspecified site: Even less specific; use C83.90 when at least 'non-follicular' characterization is available
- •C83.30 — Diffuse large B-cell lymphoma, unspecified site: Use when pathology specifically identifies diffuse large B-cell lymphoma