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ICD-10-CM 2027 diagnosis code

C50.A2Malignant inflammatory neoplasm of left breast

✓ Billable / specific

C50.A2 is a valid, billable ICD-10-CM code for malignant inflammatory neoplasm of left breast. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code last changed in FY2026 (effective October 1, 2025). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About C50.A2

C50.A2 is the ICD-10-CM diagnosis code for malignant inflammatory neoplasm of left breast. It belongs to category C50 (malignant neoplasm of breast), block C50 (malignant neoplasms of breast) and chapter 2 (neoplasms). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within C50.A (malignant inflammatory neoplasm of breast), C50.A2 is specifically for malignant inflammatory neoplasm of left breast. Related codes cover unspecified breast (C50.A0) and right breast (C50.A1).

Use an additional code to identify estrogen, and other hormones and factors receptor status (Z17.-).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 582 (Mastectomy for Malignancy with CC/MCC, relative weight 1.8006), DRG 583 (Mastectomy for Malignancy without CC/MCC, relative weight 1.8006), DRG 597 (Malignant Breast Disorders with MCC, relative weight 1.7383), DRG 598 (Malignant Breast Disorders with CC, relative weight 1.0962) and DRG 599 (Malignant Breast Disorders without CC/MCC, relative weight 0.6925), in MDC 09 (Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It was added in FY2026, effective October 1, 2025.

Notes that apply from higher levels

Instructions written at a parent level also apply to C50.A2.

› From C50 Malignant neoplasm of breast
Includes
  • connective tissue of breast
  • Paget's disease of breast
  • Paget's disease of nipple
Excludes1
Use additional code
  • code to identify estrogen, and other hormones and factors receptor status (Z17.-)

Broader instructions also apply from Chapter 2: Neoplasms.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

MDC 09 · Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2026 (effective 10/1/2025): Added
  • No changes since FY2026.

Common questions about C50.A2

Is C50.A2 billable?

Yes. C50.A2 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can C50.A2 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict C50.A2 as a principal diagnosis.

Is C50.A2 a CC or MCC?

No. C50.A2 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does C50.A2 group to?

C50.A2 is used in the MS-DRG v44.0 logic for MS-DRG 582 (Mastectomy for Malignancy with CC/MCC), MS-DRG 583 (Mastectomy for Malignancy without CC/MCC), MS-DRG 597 (Malignant Breast Disorders with MCC), MS-DRG 598 (Malignant Breast Disorders with CC) and MS-DRG 599 (Malignant Breast Disorders without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.