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C50.911 ICD-10-CM Code: Malignant neoplasm of unspecified site of right female breast

C50.911 maps to CMS-HCC V28 23. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools

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Code lookupC50.911

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

C50.911

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

Malignant neoplasm of unspecified site of right female breast

Breast cancer in a female patient affecting the right breast, but the specific location within the breast is not identified or documented.

Buddy the Bee presenting code insight

Buddy Insight

Malignant neoplasm of unspecified site of right female breast is commonly used when a breast cancer diagnosis is confirmed with laterality but the specific quadrant or subsite is not documented.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 23

Code-level coefficient reference

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

N/A

—

Not mapped

ESRD/PACE

N/A

—

Not mapped

RXHCC

HCC 22

Code-level coefficient reference

Code Book Path

Official
C50.9Malignant neoplasm of breast of unspecified siteC50.91Malignant neoplasm of breast of unspecified site, femaleC50.911Malignant neoplasm of unspecified site of right female breast

Inclusion Terms

Official

No inclusion terms are included in this display for C50.911. Check the code and parent instructions in the Code Book.

Excludes 2

Official

No Excludes 2 notes are included in this display for C50.911. Check the code and parent instructions in the Code Book.

Related Codes

Official
C50.912Malignant neoplasm of unspecified site of left female breastC50.919Malignant neoplasm of unspecified site of unspecified female breast

Includes

Official
  • connective tissue of breastInherited from C50
  • Paget's disease of breastInherited from C50
  • Paget's disease of nippleInherited from C50

Excludes 1

Official
  • skin of breast (C44.501, C44.511, C44.521, C44.591)Inherited from C50

Code First

Official

No Code First sequencing instructions are included in this display for C50.911. Check the code and parent instructions in the Code Book.

Use Additional

Official
  • code to identify estrogen, and other hormones and factors receptor status (Z17.-)Inherited from C50

Code Also

Official

No Code Also instructions are included in this display for C50.911. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance
Confirmed female patient sex
Laterality documented as right breast
Confirmation that a more specific site cannot be determined from available documentation
Histological type and grade

MEAT Support

HCC Buddy guidance
Confirmed female patient sex
Laterality documented as right breast
Confirmation that a more specific site cannot be determined from available documentation
Histological type and grade

Audit Caution

HCC Buddy guidance
Using this unspecified site code when pathology or imaging reports specify the exact quadrant or location
Confusing active breast cancer with personal history of breast cancer (Z85.3)
Not reviewing radiology reports which typically identify the tumor location precisely
Accepting the unspecified site designation without querying the provider for more detail

Common Mistakes

HCC Buddy guidance
C50.411 — Upper-outer quadrant of right female breast; use when the specific quadrant is documented
C50.811 — Overlapping sites of right female breast; use when tumor spans multiple specific sites
C50.912 — Unspecified site of left female breast; laterality confusion
C50.919 — Unspecified site of unspecified female breast; use only when laterality is also unknown

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 C50.911 an HCC code?

Yes. C50.911 (Malignant neoplasm of unspecified site of right female 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: C50.911 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
C50.911
Description
Malignant neoplasm of unspecified site of right female 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 C50.911 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C50.911

For C50.911, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

  • 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

Coder workflow notes

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What This Code Means

C50.911 is the ICD-10-CM diagnosis code for malignant neoplasm of unspecified site of right female breast. Breast cancer in a female patient affecting the right breast, but the specific location within the breast is not identified or documented. C50.911 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, C50.911 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 C50.911; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. 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.

Malignant neoplasm of unspecified site of right female breast, lesion location within the breast is unspecified but laterality is right. For C50.911, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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 C50.911 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Malignant neoplasm of unspecified site of right female breast, lesion location within the breast is unspecified but laterality is right.
  • •Prefer sub-site specificity (C50.011-C50.811) when pathology supports it. The unspecified-site codes are fallbacks for mass-diagnosis scenarios.

Clinical Significance

Malignant neoplasm of unspecified site of right female breast is commonly used when a breast cancer diagnosis is confirmed with laterality but the specific quadrant or subsite is not documented. While better than a fully unspecified code, coders should attempt to identify the specific breast location from pathology, imaging, or operative reports before accepting this designation.

Documentation Requirements

  • ✓Confirmed female patient sex
  • ✓Laterality documented as right breast
  • ✓Confirmation that a more specific site cannot be determined from available documentation
  • ✓Histological type and grade
  • ✓TNM staging
  • ✓Receptor status (estrogen receptor, progesterone receptor, HER2)
  • ✓Current treatment phase (active treatment, surveillance, or history)

Commonly Confused Codes

  • •C50.411: Upper-outer quadrant of right female breast; use when the specific quadrant is documented
  • •C50.811: Overlapping sites of right female breast; use when tumor spans multiple specific sites
  • •C50.912: Unspecified site of left female breast; laterality confusion
  • •C50.919: Unspecified site of unspecified female breast; use only when laterality is also unknown
  • •Z85.3: Personal history of malignant neoplasm of breast; use only when cancer is no longer present

Child Codes

C50.911Malignant neoplasm of unspecified site of right female breast
HCC 22
C50.912Malignant neoplasm of unspecified site of left female breast
HCC 22
C50.919Malignant neoplasm of unspecified site of unspecified female breast
HCC 22

Code Hierarchy

└C50Malignant neoplasm of breast└C50.9Malignant neoplasm of breast of unspecified site└C50.91Malignant neoplasm of breast of unspecified site, female└C50.911Malignant neoplasm of unspecified site of right female breast
└C50.911Malignant neoplasm of unspecified site of right female breast

Also searched as

  • breast cancer
  • CA breast

For C50.911, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

C50.911 maps to CMS-HCC V28 category 23, Prostate, Breast, and Other Cancers and Tumors. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for C50.911. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

More on C50.911

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