C41.4
BillableMalignant neoplasm of pelvic bones, sacrum and coccyx
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C41.4 an HCC code?
Yes. C41.4 maps to Lymphoma and Other Cancers 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 C41.4
For C41.4to 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 C41.4 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C41.4 is the ICD-10-CM diagnosis code for malignant neoplasm of pelvic bones, sacrum and coccyx. This code represents cancer that originates in the bones of the pelvis, sacrum (the large triangular bone at the base of the spine), or coccyx (tailbone). These are primary bone cancers rather than cancer that has spread to these bones from elsewhere. C41.4 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of bone and articular cartilage (c40-c41).
Under the CMS-HCC V28 risk adjustment model, C41.4 maps to Lymphoma and Other Cancers (HCC 21) with a community, non-dual, aged base RAF weight of 0.671. Under the older V24 model, C41.4 mapped to the same category but with a base RAF weight of 0.675 — 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.
Verify whether the cancer is primary (originated in the bone) or secondary (metastatic from another site), as secondary bone cancers use different codes. Because C41.4 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 C41.4 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify whether the cancer is primary (originated in the bone) or secondary (metastatic from another site), as secondary bone cancers use different codes
- •Document the specific bone location (pelvis, sacrum, or coccyx) in the medical record to support accurate code selection and ensure specificity
Clinical Significance
Primary malignant neoplasm of the pelvic bones, sacrum, and coccyx. This site includes chordoma (most common sacral tumor), chondrosarcoma, osteosarcoma, and Ewing sarcoma of the pelvis. These tumors are often large at diagnosis due to the deep anatomic location and carry significant surgical morbidity. Distinction from pelvic metastases is critical.
Documentation Requirements
- ✓Specific bone involved (ilium, ischium, pubis, sacrum, or coccyx)
- ✓Histologic type — sacral chordoma is the most common primary sacral tumor
- ✓Primary vs. metastatic origin confirmed — pelvic bone metastases are far more common
- ✓Tumor staging and imaging extent
- ✓Involvement of sacral nerve roots or pelvic organs
- ✓Treatment plan and functional impact assessment
Commonly Confused Codes
- •C41.2 — Malignant neoplasm of vertebral column; the sacrum is coded under C41.4, NOT C41.2
- •C79.51 — Secondary malignant neoplasm of bone; pelvic metastases from prostate, breast, and colon cancer are very common
- •C76.3 — Malignant neoplasm of pelvis; this is for unspecified pelvic site, not bone-specific
- •C41.0 — Malignant neoplasm of skull/face; different axial site