What is ICD-10 code C50.129?

C50.129 is the ICD-10-CM diagnosis code for Malignant neoplasm of central portion of unspecified male breast. Cancer in the central portion of a male breast where the specific side (left or right) is not identified. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C50.129 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C50.129 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. C50.129 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. C50.129 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does C50.129 map to under V28?

C50.129 maps to CMS-HCC V28 HCC 23 (Prostate, Breast, and Other Cancers and Tumors). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

What documentation supports C50.129?

This unspecified code should only be used when laterality cannot be determined from documentation Query the provider if possible to determine whether the cancer is in the right or left breast for more specific coding Because C50.129 maps to an HCC category, the documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. See the MEAT criteria checklist at /meat-criteria for what Monitor, Evaluate, Assess, or Treat looks like in a note. MEAT is generic documentation evidence, not a payer-specific rule.

2026 ICD-10-CM C50.129: Malignant neoplasm

C50.129 maps to CMS-HCC V28 23. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · HCC coding software

ICD-10-CM Code View

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Code lookupC50.129Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of breast (C50)

C50.129

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

Malignant neoplasm of central portion of unspecified male breast

Cancer in the central portion of a male breast where the specific side (left or right) is not identified.

Buddy Insight

Malignant neoplasm of the central portion of unspecified male breast represents invasive breast cancer requiring staging, treatment planning, and ongoing surveillance.

CMS-HCC V28

Mapped

HCC 23

Prostate, Breast, and Other C...

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

N/A

—

Not risk-adjusted for this model/period.

Not mapped

ESRD/PACE

N/A

—

Not risk-adjusted for this model/period.

Not mapped

RXHCC

Mapped

HCC 22

Prostate, Breast, Bladder, an...

Code-level coefficient reference

Code Book Path

Official

C50.1Malignant neoplasm of central portion of breast

C50.12Malignant neoplasm of central portion of breast, male

C50.129Malignant neoplasm of central portion of unspecified male breast

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for C50.129 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C50.129 in this effective period.

Related Child Codes

Official

C50.121Malignant neoplasm of central portion of right male breast

C50.122Malignant neoplasm of central portion of left male breast

Includes

Official

ICD-10-CM does not list Includes notes for C50.129 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for C50.129 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C50.129 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C50.129 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C50.129 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Pathologic confirmation of invasive malignancy (biopsy with histologic type — ductal, lobular, etc.)

Laterality must be queried if not documented — right or left breast

Gender documented as male to support gender-specific code selection

Quadrant or subsite location: central portion

MEAT Support

HCC Buddy guidance

Pathologic confirmation of invasive malignancy (biopsy with histologic type — ductal, lobular, etc.)

Laterality must be queried if not documented — right or left breast

Gender documented as male to support gender-specific code selection

Quadrant or subsite location: central portion

Audit Caution

HCC Buddy guidance

Selecting female breast codes (C50.11x) instead of male-specific codes (C50.12x)

Confusing central portion with nipple/areola — different subsites with different code assignments

Coding gynecomastia (N62) or benign conditions as malignancy in male patients

Not querying for laterality when using unspecified codes

Common Mistakes

HCC Buddy guidance

C50.121 — Right male breast central portion; preferred when right documented

C50.122 — Left male breast central portion; preferred when left documented

C50.119 — Same laterality but female breast; verify patient gender

C50.021-C50.029 — Nipple and areola of male breast; central portion is distinct from the nipple-areolar complex

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 C50.129 an HCC code?

Yes. C50.129 (Malignant neoplasm of central portion of unspecified male breast) maps to HCC 23, Prostate, Breast, and Other Cancers and Tumors under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.186. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: C50.129 is billable and maps to V28 HCC 23, Prostate, Breast, and Other Cancers and Tumors. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C50.129
Description: Malignant neoplasm of central portion of unspecified male breast
HCC (V28): HCC 23 — Prostate, Breast, and Other Cancers and Tumors
RAF reference coefficient: 0.186
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 23, Prostate, Breast, and Other Cancers and Tumors

0.186

RxHCCHCC 22, Prostate, Breast, Bladder, and Other Cancers and Tumors

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. 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 context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work C50.129 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for C50.129

For C50.129 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 C50.129 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

C50.129 is the ICD-10-CM diagnosis code for malignant neoplasm of central portion of unspecified male breast. Cancer in the central portion of a male breast where the specific side (left or right) is not identified. C50.129 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, C50.129 maps to Prostate, Breast, and Other Cancers and Tumors (HCC 23) with a source-labeled community, non-dual, aged reference coefficient of 0.186. No V24 mapping is shown for C50.129; use the applicable model and payment year when reviewing the V28 mapping. 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. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

This unspecified code should only be used when laterality cannot be determined from documentation. Because C50.129 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. 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, source-labeled coefficient references, and MEAT documentation criteria for C50.129 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This unspecified code should only be used when laterality cannot be determined from documentation
•Query the provider if possible to determine whether the cancer is in the right or left breast for more specific coding

Clinical Significance

Malignant neoplasm of the central portion of unspecified male breast represents invasive breast cancer requiring staging, treatment planning, and ongoing surveillance. Breast cancer is risk-adjusted because it demands significant healthcare resources including surgery, radiation, chemotherapy, hormonal therapy, and long-term monitoring. Male breast cancer accounts for less than 1% of all breast cancers, making accurate gender-specific coding particularly important for tracking and research. The unspecified laterality indicates documentation does not identify the affected side, which should trigger a provider query.

Documentation Requirements

✓Pathologic confirmation of invasive malignancy (biopsy with histologic type — ductal, lobular, etc.)
✓Laterality must be queried if not documented — right or left breast
✓Gender documented as male to support gender-specific code selection
✓Quadrant or subsite location: central portion
✓Tumor size (T stage) and grade
✓Lymph node status (N stage) — axillary, sentinel node biopsy results
✓Estrogen receptor, progesterone receptor, and HER2 status
✓Stage grouping (I-IV)
✓Current treatment status (active treatment, hormonal therapy, surveillance)

Commonly Confused Codes

•C50.121: Right male breast central portion; preferred when right documented
•C50.122: Left male breast central portion; preferred when left documented
•C50.119: Same laterality but female breast; verify patient gender
•C50.021-C50.029: Nipple and areola of male breast; central portion is distinct from the nipple-areolar complex
•N62: Gynecomastia; benign, not malignant: do not confuse with male breast cancer
•D05.1x: Carcinoma in situ of breast; in situ vs. invasive distinction

Child Codes

C50.121Malignant neoplasm of central portion of right male breast

HCC 22

C50.122Malignant neoplasm of central portion of left male breast

HCC 22

C50.129Malignant neoplasm of central portion of unspecified male breast

HCC 22

Code Hierarchy

└C50Malignant neoplasm of breast └C50.1Malignant neoplasm of central portion of breast └C50.12Malignant neoplasm of central portion of breast, male └C50.129Malignant neoplasm of central portion of unspecified male breast

└C50.129Malignant neoplasm of central portion of unspecified male breast

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C50.129

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MEAT Criteria for C50.129

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Commonly Confused Codes

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C50.129 ICD-10-CM Code: Malignant neoplasm of central portion of unspecified male breast

HCC Buddy Code Card

C50.129

Is C50.129 an HCC code?

HCC Category Mapping

MEAT Criteria for C50.129

Get the V28 mapping + MEAT cheat sheet

What This Code Means

Coding Tips

Clinical Significance

Documentation Requirements

Commonly Confused Codes

Child Codes

Code Hierarchy

More on C50.129

Related condition guides

Work C50.129 in HCC Buddy