C57.22
BillableMalignant neoplasm of left round ligament
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C57.22 an HCC code?
Yes. C57.22 maps to Colorectal, Bladder, 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 C57.22
For C57.22 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 C57.22 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C57.22 is the ICD-10-CM diagnosis code for malignant neoplasm of left round ligament. This code describes cancer that has developed in the left round ligament, which is a structure in the female reproductive system that helps support the uterus. This is a type of gynecological cancer affecting the ligament tissue itself. C57.22 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of female genital organs (c51-c58).
Under the CMS-HCC V28 risk adjustment model, C57.22 maps to Colorectal, Bladder, and Other Cancers (HCC 22) with a community, non-dual, aged base RAF weight of 0.000. Under the older CMS-HCC V24 model, C57.22 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.
Ensure documentation specifies the left side; if the round ligament cancer is on the right side, use C57.21 instead, and for unspecified side use C57.20. Because C57.22 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 C57.22 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Ensure documentation specifies the left side; if the round ligament cancer is on the right side, use C57.21 instead, and for unspecified side use C57.20
- •Verify that the malignancy is primary to the round ligament itself rather than metastatic cancer from another site, as this affects code selection
Clinical Significance
Left round ligament malignancy is an exceedingly rare tumor that may present as a left inguinal mass. Precise anatomical identification differentiates this from benign conditions like inguinal hernia or cyst of the canal of Nuck. Accurate laterality supports cancer registry reporting and treatment planning.
Documentation Requirements
- ✓Documentation specifying left-sided round ligament involvement
- ✓Pathologic confirmation of malignancy with histologic type
- ✓Staging information
- ✓Primary versus metastatic determination
- ✓Current treatment status