C26.1
BillableMalignant neoplasm of spleen
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C26.1 an HCC code?
Yes. C26.1 maps to Colorectal, Bladder, and Other Cancers under the CMS-HCC V28 risk adjustment model (and Colorectal, Bladder, 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 C26.1
For C26.1to 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 C26.1 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C26.1 is the ICD-10-CM diagnosis code for malignant neoplasm of spleen. Cancer that develops in the spleen, a lymphoid organ located in the upper left abdomen. C26.1 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of digestive organs (c15-c26).
Under the CMS-HCC V28 risk adjustment model, C26.1 maps to Colorectal, Bladder, and Other Cancers (HCC 22) with a community, non-dual, aged base RAF weight of 0.000. Under the older V24 model, C26.1 mapped to the same category but with a base RAF weight of 0.306 — 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.
Distinguish between primary splenic cancer and secondary involvement from other malignancies. Because C26.1 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 C26.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Distinguish between primary splenic cancer and secondary involvement from other malignancies
- •Confirm whether this is lymphoma or another type of splenic malignancy based on pathology findings
Clinical Significance
Primary splenic malignancies are rare — most splenic cancers are secondary (metastatic) or lymphomatous involvement. When coding primary splenic cancer, it is critical to confirm the malignancy originates in the spleen rather than involving it secondarily. This distinction affects both treatment approach and accurate risk adjustment capture.
Documentation Requirements
- ✓Pathology confirmation of primary splenic malignancy (not metastatic spread)
- ✓Histological type (angiosarcoma, lymphoma, etc.)
- ✓Imaging confirming primary splenic origin
- ✓Documentation distinguishing primary from secondary splenic involvement
- ✓Treatment status and clinical stage
Commonly Confused Codes
- •C83-C85 — Non-Hodgkin lymphoma codes: Splenic lymphomas should be coded with lymphoma-specific codes, not C26.1
- •C81 — Hodgkin lymphoma: Splenic involvement in Hodgkin disease uses lymphoma codes with site modifier
- •C78.89 — Secondary malignant neoplasm of other digestive organs: Use for metastatic cancer involving the spleen
- •D73.4 — Cyst of spleen: Ensure splenic masses are confirmed malignant before coding C26.1