ICD10
ICD-10 Code C50.5: Malignant neoplasm of lower-outer quadrant of breast
Reviewed by HealthAssure Clinical TeamUpdated 26 May 2026
What is this code?
ICD-10 entries help standardize how diagnoses are organized for coding, reporting, analytics, and documentation. This code sits within the broader ICD-10 area for Neoplasms (C00-D49).
When is it used?
- May be used when a clinician documents malignant neoplasm of lower-outer quadrant of breast in a patient's medical record.
- May appear in hospital records, claims, referrals, and clinical documentation.
- This code may act more like a grouping or parent code, so a more specific child code may be used in final documentation when available.
What it does not mean
- A code alone does not explain severity, treatment plan, or outcome.
- A medical code should not be treated as a substitute for a doctor's diagnosis or advice.
- This entry may represent a broader category rather than the most specific billable code.
Code hierarchy
chapter
2Neoplasms (C00-D49)
block
C00-C96Malignant neoplasms
block
C00-C75Malignant neoplasms, stated or presumed to be primary (of specified sites), and certain specified histologies, except neuroendocrine, and of lymphoid, hematopoietic and related tissue
block
C50Malignant neoplasms of breast (C50)
category
C50Malignant neoplasm of breast
currentC50
Where you may see this code
You may see this entry in coding references, medical records, or claims workflows when a broader diagnosis category is being reviewed before a more specific code is chosen.
Related specialists
OncologistGeneral PhysicianBreast Surgeon
Related codes
C50Malignant neoplasm of breastcategoryC50.0Malignant neoplasm of nipple and areolacategoryC50.1Malignant neoplasm of central portion of breastcategoryC50.2Malignant neoplasm of upper-inner quadrant of breastcategoryC50.3Malignant neoplasm of lower-inner quadrant of breastcategoryC50.4Malignant neoplasm of upper-outer quadrant of breastcategoryC50.6Malignant neoplasm of axillary tail of breastcategoryC50.8Malignant neoplasm of overlapping sites of breastcategoryC50.9Malignant neoplasm of breast of unspecified sitecategoryC50.AMalignant inflammatory neoplasm of breastcategory
Sibling codes
C50Malignant neoplasm of breastC50.0Malignant neoplasm of nipple and areolaC50.1Malignant neoplasm of central portion of breastC50.2Malignant neoplasm of upper-inner quadrant of breastC50.3Malignant neoplasm of lower-inner quadrant of breastC50.4Malignant neoplasm of upper-outer quadrant of breastC50.6Malignant neoplasm of axillary tail of breastC50.8Malignant neoplasm of overlapping sites of breastC50.9Malignant neoplasm of breast of unspecified siteC50.AMalignant inflammatory neoplasm of breast
Mapped diagnoses and classifications
SNOMED_CT 286896005high
Carcinoma breast - lower, outer quadrant
Source: SNOMED International ICD-10 map
SNOMED_CT 1306572003high
Infiltrating duct carcinoma of lower outer quadrant of breast
Source: SNOMED International ICD-10 map
SNOMED_CT 1306574002high
Infiltrating duct carcinoma of lower outer quadrant of left breast
Source: SNOMED International ICD-10 map
SNOMED_CT 1306573008high
Infiltrating duct carcinoma of lower outer quadrant of right breast
Source: SNOMED International ICD-10 map
SNOMED_CT 373081007high
Malignant neoplasm of lower outer quadrant of breast
Source: SNOMED International ICD-10 map
SNOMED_CT 1259421001high
Primary carcinoma breast - lower, outer quadrant
Source: SNOMED International ICD-10 map
Coding guidelines
Compatibility
Legacy code aligns to an official FY 2026 category. Frontend should resolve to the official category page and surface the billable child codes.
Legacy codes
C50.5
Common synonyms
Malignant neoplasm of lower-outer quadrant of breast
Frequently asked questions
About this content
This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.