C40.80
BillableMalignant neoplasm of overlapping sites of bone and articular cartilage of unspecified limb
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C40.80 an HCC code?
Yes. C40.80 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 C40.80
For C40.80to 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 C40.80 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C40.80 is the ICD-10-CM diagnosis code for malignant neoplasm of overlapping sites of bone and articular cartilage of unspecified limb. Cancer that starts in bone or cartilage where multiple areas overlap in an unspecified arm or leg. C40.80 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, C40.80 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, C40.80 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.
Use this code only when the specific limb (right or left) is not documented; query provider if laterality is known. Because C40.80 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 C40.80 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when the specific limb (right or left) is not documented; query provider if laterality is known
- •This code indicates overlapping sites, meaning the tumor involves more than one bone or cartilage area
Clinical Significance
Primary malignant neoplasm of overlapping sites of bone and articular cartilage of an unspecified limb. This code is used when a bone tumor spans multiple contiguous anatomic sites within a single limb and cannot be assigned to a single bone location. The unspecified limb designation indicates documentation gaps that should be addressed.
Documentation Requirements
- ✓Description of which overlapping bone sites are involved
- ✓Attempt to clarify laterality through provider query
- ✓Histologic type and grade from pathology
- ✓Primary vs. metastatic origin confirmed
- ✓Imaging showing tumor extent across multiple bone sites
- ✓Reason the specific limb (upper/lower, right/left) is not determinable
Commonly Confused Codes
- •C40.81 — Overlapping sites of bone/cartilage of RIGHT limb; use when right side is documented
- •C40.82 — Overlapping sites of bone/cartilage of LEFT limb; use when left side is documented
- •C40.90 — Unspecified bones of unspecified limb; use when sites are not overlapping but simply unspecified
- •C41.9 — Malignant neoplasm of bone/cartilage, unspecified; for non-limb bone cancers that are unspecified