FY2027 ICD-10-CM reference
C50.519: Malignant neoplasm of lower-outer quadrant of unspecified female breast
By the HCC Buddy Coding Team
The official ICD-10-CM descriptor is Malignant neoplasm of lower-outer quadrant of unspecified female breast. The FY2027 annual edition starts October 1, 2026. Check the edition that applies to the encounter or inpatient discharge, including any April update.
Billable code. Verified against the official FY2027 order file.
FY2027 Tabular instructions
Instructions below include applicable chapter, section and parent-code notes. Each note identifies where it appears in the official source.
Instructional note
Functional activity
Source: C00-D49 (chapter, inherited).
Instructional note
All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
Source: C00-D49 (chapter, inherited).
Instructional note
Morphology [Histology]
Source: C00-D49 (chapter, inherited).
Instructional note
Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
Source: C00-D49 (chapter, inherited).
Instructional note
Primary malignant neoplasms overlapping site boundaries
Source: C00-D49 (chapter, inherited).
Instructional note
A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
Source: C00-D49 (chapter, inherited).
Instructional note
Malignant neoplasm of ectopic tissue
Source: C00-D49 (chapter, inherited).
Instructional note
Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).
Source: C00-D49 (chapter, inherited).
Includes
connective tissue of breast
Source: C50 (category, inherited).
Includes
Paget's disease of breast
Source: C50 (category, inherited).
Includes
Paget's disease of nipple
Source: C50 (category, inherited).
Instructional note
code to identify estrogen, and other hormones and factors receptor status (Z17.-)
Source: C50 (category, inherited).
Excludes1
skin of breast (C44.501, C44.511, C44.521, C44.591)
Source: C50 (category, inherited).
Compare the FY2027 additions, removals and billable-status changes
What does C50.519 mean in FY2027?
The official ICD-10-CM descriptor is Malignant neoplasm of lower-outer quadrant of unspecified female breast. The FY2027 annual edition starts October 1, 2026. Check the edition that applies to the encounter or inpatient discharge, including any April update.
Is C50.519 billable in FY2027?
The FY2027 order file marks C50.519 as billable. Check the complete Tabular instructions and documentation before assigning it.
Does C50.519 map to an HCC?
In the CMS 2027 Initial ICD-10-CM Mappings (payment year 2027, 2026 dates of service), C50.519 maps to CMS-HCC V28 HCC 23 (Prostate, Breast, and Other Cancers and Tumors). For 2027 dates of service, CMS has not yet published the payment year 2028 mappings. ESRD, RxHCC, PACE and HHS-HCC mappings are still pending verification for FY2027.
Source: CMS FY2027 ICD-10-CM order file. Read the FY2027 Official Guidelines.
Review the FY2026 April edition