2026 ICD-10-CM Diagnosis Code C50.519Malignant neoplasm of lower-outer quadrant of unspecified female breast

ICD-10-CM Codes›C00–D49›C50›C50

ICD-10-CM C50.519
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C50.519 is a billable ICD-10-CM diagnosis code for malignant neoplasm of lower-outer quadrant of unspecified female breast. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 582 through 583, 597 through 599. Coders also document this condition as carcinoma breast - lower, outer quadrant. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Breast cancer - all other types.

Code Identity

ICD-10-CM Code
C50.519
Billable Status
Yes — Valid for Submission
Code Describes
Malignant neoplasm of lower-outer quadrant of unspecified female breast
Short Description
Malig neoplasm of lower-outer quadrant of unsp female breast
Parent Code
C50.51
Malignant neoplasm of lower-outer quadrant of breast, female

Code Classification

ChapterC00–D49Neoplasms
SectionC50Malignant neoplasms of breast
CategoryC50Malignant neoplasm of breast
This CodeC50.519Malignant neoplasm of lower-outer quadrant of unspecified female breast

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Carcinoma breast - lower, outer quadrant
  • Infiltrating duct carcinoma of lower outer quadrant of breast
  • Malignant neoplasm of lower outer quadrant of breast
  • Primary carcinoma breast - lower, outer quadrant
  • Primary carcinoma of breast
  • Primary infiltrating duct carcinoma of lower outer quadrant of breast
  • Primary malignant neoplasm of lower outer quadrant of breast
  • Sarcoma of breast
  • Sarcoma of lower outer quadrant of breast

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NEO030
Breast cancer - all other types
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Breast Cancer

Breast cancer is a cancer that starts in breast tissue. It happens when cells in the breast change and grow out of control. New cells grow even when you don't need them, and old cells don't die when they should. These extra cells can form a mass called a tumor.

The full article covers:

  • What is breast cancer?
  • What are the types of breast cancer?
  • What causes breast cancer?
  • Who is at risk for breast cancer?
  • What are the signs and symptoms of breast cancer?
  • How is breast cancer diagnosed?
  • What are the treatments for breast cancer?
  • Can breast cancer be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert C50.519 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
174.5 Mal neo breast low-outer
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About C50.519Overview

Is C50.519 (Malignant neoplasm of lower-outer quadrant of breast, female) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of lower-outer quadrant of unspecified female breast on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does C50.519 group to?

When malignant neoplasm of lower-outer quadrant of unspecified female breast is the principal diagnosis on an inpatient stay, it groups to MS-DRG 582, 583, 597, 598, 599, with relative weights from 0.7332 to 1.9266 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of C50.519?

Under the General Equivalence Mappings, malignant neoplasm of lower-outer quadrant of unspecified female breast converts to ICD-9-CM 174.5 (mal neo breast low-outer). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.