N63.21 ICD-10-CM Code: Unspecified lump in the left breast, upper outer quadrant
Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.
Inpatient Payment Groups (MS-DRG)
MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43.0 (FY2026), Appendix B.
- MS-DRG 600 — NON-MALIGNANT BREAST DISORDERS WITH CC/MCC (MDC 09)
- MS-DRG 601 — NON-MALIGNANT BREAST DISORDERS WITHOUT CC/MCC (MDC 09)
A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.
Code Set: Valid FY2026 and FY2027. FY2026 took effect October 1, 2025.
Official Registry Overview & Definition
Official Tabular Instructional Notes
Sequencing, inclusion, and exclusion notes published for N63.21 in the official ICD-10-CM tabular list.
Excludes1 — Not Coded Here
Conditions that can never be reported with this code; the two are mutually exclusive.
- disorders of breast associated with childbirth (O91-O92)
Nearest Codes in This Family
Official ICD-10-CM classifications closest to N63.21 in its code family, with their registry titles.
- N63.13 — Unspecified lump in the right breast, lower outer quadrant
- N63.14 — Unspecified lump in the right breast, lower inner quadrant
- N63.15 — Unspecified lump in the right breast, overlapping quadrants
- N63.2 — Unspecified lump in the left breast
- N63.20 — Unspecified lump in the left breast, unspecified quadrant
- N63.22 — Unspecified lump in the left breast, upper inner quadrant
- N63.23 — Unspecified lump in the left breast, lower outer quadrant
- N63.24 — Unspecified lump in the left breast, lower inner quadrant
- N63.25 — Unspecified lump in the left breast, overlapping quadrants
- N63.3 — Unspecified lump in axillary tail
Indexed Clinical Terms (1)
Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code.
- Lump, breast, left, upper outer quadrant