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C50.629 ICD-10-CM Code: Malignant neoplasm of axillary tail of unspecified male breast

C50.629 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)

C50.629

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Malignant neoplasm of axillary tail of unspecified male breast

Cancer in the axillary tail of a male breast when the specific side (left or right) is not documented or unknown.

Buddy the Bee presenting code insight

Buddy Insight

This unspecified laterality code for axillary tail breast cancer in males reflects a documentation gap that should be addressed.

CMS-HCC V28

HCC 22

RAF 0.363

CMS-HCC V24

HCC 12

RAF 0.150

ACA/HHS

N/A

—

Not mapped

ESRD/PACE

HCC 12

RAF 0.045

RXHCC

HCC 22

RAF 0.124

Code Book Path

Official
C50.6Malignant neoplasm of axillary tail of breast
C50.62Malignant neoplasm of axillary tail of breast, male
C50.629Malignant neoplasm of axillary tail of unspecified male breast

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for C50.629 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C50.629 in this effective period.

Related Child Codes

Official
C50.621Malignant neoplasm of axillary tail of right male breast
C50.622Malignant neoplasm of axillary tail of left male breast

Includes

Official

ICD-10-CM does not list Includes notes for C50.629 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for C50.629 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C50.629 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C50.629 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C50.629 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Confirmed male patient sex
Site confirmed as axillary tail
Documentation explaining why laterality is unavailable
Evidence of provider query for laterality

MEAT Support

HCC Buddy guidance
Confirmed male patient sex
Site confirmed as axillary tail
Documentation explaining why laterality is unavailable
Evidence of provider query for laterality

Audit Caution

HCC Buddy guidance
Using unspecified laterality as a default without attempting to determine the affected side
Failing to check operative reports, imaging, or physical exam findings for laterality
Not recognizing that virtually all surgical or imaging documentation specifies laterality

Common Mistakes

HCC Buddy guidance
C50.621 — Axillary tail of right male breast; use when right is confirmed
C50.622 — Axillary tail of left male breast; use when left is confirmed
C50.929 — Unspecified site of unspecified male breast; even less specific code

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 C50.629 an HCC code?

Yes. C50.629 (Malignant neoplasm of axillary tail of unspecified male 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: C50.629 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
C50.629
Description
Malignant neoplasm of axillary tail of unspecified male breast
HCC (V28)
HCC 22 — Bladder, Colorectal, and Other Cancers
RAF
0.363
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 22, Bladder, Colorectal, and Other Cancers
0.363
V24HCC 12, Breast, Prostate, and Other Cancers and Tumors
0.150
ESRDHCC 12, Breast, Prostate, and Other Cancers and Tumors
0.045
RxHCCHCC 22, Cancer, Other Specified Sites
0.124

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 C50.629 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for C50.629

For C50.629 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 C50.629 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

C50.629 is the ICD-10-CM diagnosis code for malignant neoplasm of axillary tail of unspecified male breast. Cancer in the axillary tail of a male breast when the specific side (left or right) is not documented or unknown. C50.629 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, C50.629 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, C50.629 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.

Use this code only when laterality cannot be determined; if known, use C50.621 or C50.622. Because C50.629 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 C50.629 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 laterality cannot be determined; if known, use C50.621 or C50.622
  • •Query the provider for laterality clarification, as male breast cancer documentation should be precise

Clinical Significance

This unspecified laterality code for axillary tail breast cancer in males reflects a documentation gap that should be addressed. Given the clinical significance and rarity of male breast cancer, every effort should be made to determine laterality. Unspecified codes compromise cancer registry data quality and may trigger compliance reviews.

Documentation Requirements

  • ✓Confirmed male patient sex
  • ✓Site confirmed as axillary tail
  • ✓Documentation explaining why laterality is unavailable
  • ✓Evidence of provider query for laterality
  • ✓Review of imaging and surgical records attempted

Commonly Confused Codes

  • •C50.621: Axillary tail of right male breast; use when right is confirmed
  • •C50.622: Axillary tail of left male breast; use when left is confirmed
  • •C50.929: Unspecified site of unspecified male breast; even less specific code

Child Codes

C50.621Malignant neoplasm of axillary tail of right male breast
HCC 22
C50.622Malignant neoplasm of axillary tail of left male breast
HCC 22
C50.629Malignant neoplasm of axillary tail of unspecified male breast
HCC 22

Code Hierarchy

└C50Malignant neoplasm of breast└C50.6Malignant neoplasm of axillary tail of breast└C50.62Malignant neoplasm of axillary tail of breast, male└C50.629Malignant neoplasm of axillary tail of unspecified male breast
└C50.629Malignant neoplasm of axillary tail of unspecified male breast

Because C50.629 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

C50.629 maps to CMS-HCC V28 category 22, Bladder, Colorectal, and Other Cancers. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. Because C50.629 carries a payment HCC, you can see what it adds to a RAF score and check the documentation the chart needs before it is submitted.

More on C50.629

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