C50.419 ICD-10-CM Code: Malignant neoplasm of upper-outer quadrant of unspecified female breast
C50.419 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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FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of breast (C50)
C50.419
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceMalignant neoplasm of upper-outer quadrant of unspecified female breast
Cancer in the upper-outer area of the breast in women when the specific side (left or right) is not documented or known.
Buddy Insight
Malignant neoplasm of the upper-outer quadrant of unspecified female breast represents invasive breast cancer requiring staging, treatment planning, and ongoing surveillance.
CMS-HCC V28
MappedHCC 23
Coefficient HCC 23: 0.186 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
Context neededHCC 011, HCC 012
Coefficient needs member context
ESRD/PACE
Context neededHCC 12
Coefficient needs member context
RXHCC
MappedHCC 22
Code-level coefficient reference
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for C50.419. Check the code and parent instructions in the Code Book.
Excludes 2
OfficialNo Excludes 2 notes are included in this display for C50.419. Check the code and parent instructions in the Code Book.
Related Codes
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
OfficialNo Code First sequencing instructions are included in this display for C50.419. 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
OfficialNo Code Also instructions are included in this display for C50.419. Check the code and parent instructions in the Code Book.
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 C50.419 an HCC code?
Yes. C50.419 (Malignant neoplasm of upper-outer quadrant of unspecified 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: C50.419 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
- C50.419
- Description
- Malignant neoplasm of upper-outer quadrant of unspecified 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
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 C50.419 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for C50.419
For C50.419, 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
C50.419 is the ICD-10-CM diagnosis code for malignant neoplasm of upper-outer quadrant of unspecified female breast. Cancer in the upper-outer area of the breast in women when the specific side (left or right) is not documented or known. C50.419 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, C50.419 maps to Prostate, Breast, and Other Cancers and Tumors (HCC 23) with a source-labeled community, non-dual, aged reference coefficient of 0.186. 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 upper-outer quadrant of unspecified female breast, laterality not documented. This is a query target whenever lateralizing information is in the operative note or imaging. For C50.419, 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 C50.419 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Malignant neoplasm of upper-outer quadrant of unspecified female breast, laterality not documented. This is a query target whenever lateralizing information is in the operative note or imaging.
- •Unspecified laterality in breast cancer is rare in well-documented charts. Prefer C50.411 or C50.412 when the surgical pathology identifies the side.
Clinical Significance
Malignant neoplasm of the upper-outer quadrant of unspecified female 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. 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 female to support gender-specific code selection
- ✓Quadrant or subsite location: upper-outer quadrant
- ✓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
- •C50.411: Right female; preferred when right documented
- •C50.412: Left female; preferred when left documented
- •C50.429: Same laterality but male breast; verify patient gender
- •C50.211-C50.219: Upper-inner quadrant; most common confusion: upper-outer is lateral (toward axilla), upper-inner is medial (toward sternum)
- •C50.511-C50.519: Lower-outer quadrant; same lateral orientation but lower position
- •C50.811-C50.819: Overlapping sites; use when tumor spans multiple quadrants