C50.611 ICD-10-CM Code: Malignant neoplasm of axillary tail of right female breast
C50.611 maps to CMS-HCC V28 22 (RAF 0.363). Documentation must support MEAT. MEAT criteria · RAF calculator · HCC Buddy coding tools
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FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of breast (C50)
C50.611
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceMalignant neoplasm of axillary tail of right female breast
Cancer that develops in the axillary tail (the extension of breast tissue toward the armpit) of the right female breast.
Buddy Insight
Cancer of the axillary tail of the right female breast involves the extension of breast tissue that projects toward the axilla (armpit).
CMS-HCC V28
MappedHCC 22
RAF 0.363
CMS-HCC V24
MappedHCC 12
RAF 0.150
ACA/HHS
N/A—
Not mapped
ESRD/PACE
MappedHCC 12
RAF 0.045
RXHCC
MappedHCC 22
RAF 0.124
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for C50.611 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for C50.611 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for C50.611 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for C50.611 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for C50.611 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for C50.611 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for C50.611 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is C50.611 an HCC code?
Yes. C50.611 (Malignant neoplasm of axillary tail of right female breast) maps to Bladder, Colorectal, and Other Cancers under the CMS-HCC V28 risk adjustment model (and Breast, Prostate, and Other Cancers and Tumors under V24), with a community non-dual aged RAF of 0.363. It is billable for payment year 2026.
Coder answer: C50.611 is billable and maps to V28 HCC 22, Bladder, Colorectal, and Other Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- C50.611
- Description
- Malignant neoplasm of axillary tail of right female breast
- HCC (V28)
- HCC 22 — Bladder, Colorectal, and Other Cancers
- RAF
- 0.363
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. 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.
Work C50.611 in the Code Book — tabular path, V28 RAF, and MEAT checklist →
MEAT Criteria for C50.611
For C50.611 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 C50.611 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
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What This Code Means
C50.611 is the ICD-10-CM diagnosis code for malignant neoplasm of axillary tail of right female breast. Cancer that develops in the axillary tail (the extension of breast tissue toward the armpit) of the right female breast. C50.611 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of breast (c50).
Under the CMS-HCC V28 risk adjustment model, C50.611 maps to Bladder, Colorectal, and Other Cancers (HCC 22) with a community, non-dual, aged base RAF weight of 0.363. Under the older CMS-HCC V24 model, C50.611 maps to Breast, Prostate, and Other Cancers and Tumors (HCC 12) with a community, non-dual, aged base RAF weight of 0.150. 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.
The axillary tail is an important anatomical location as it extends into the armpit region and may involve lymph nodes. Because C50.611 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 C50.611 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •The axillary tail is an important anatomical location as it extends into the armpit region and may involve lymph nodes
- •Verify laterality is documented as 'right' before assigning this code; left-sided tumors require C50.612
Clinical Significance
Cancer of the axillary tail of the right female breast involves the extension of breast tissue that projects toward the axilla (armpit). This anatomical location has particular clinical significance because tumors here may directly involve or be adjacent to axillary lymph nodes, potentially affecting staging and the extent of surgical dissection required.
Documentation Requirements
- ✓Confirmed female patient sex
- ✓Laterality documented as right breast
- ✓Specific site identified as axillary tail (tail of Spence)
- ✓Relationship to axillary lymph nodes documented
- ✓Histological type and grade
- ✓TNM staging including lymph node status
- ✓Imaging confirming the axillary tail location versus primary axillary lymph node disease
Commonly Confused Codes
- •C50.411: Upper-outer quadrant of right female breast; the axillary tail extends beyond the upper-outer quadrant into the axilla
- •C77.3: Secondary malignant neoplasm of axillary lymph nodes; axillary tail cancer is a primary breast cancer, not lymph node metastasis
- •C50.811: Overlapping sites of right female breast; use when tumor spans multiple sites, not when confined to axillary tail
- •C50.612: Axillary tail of left female breast; laterality error