N65.1 vs Z42.1
N65.1 (Disproportion of reconstructed breast) compared with Z42.1 (Encounter for breast reconstruction following mastectomy), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. Z42.1 carries an Excludes1 note covering N65.1: “deformity and disproportion of reconstructed breast (N65.1-)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| N65.1Disproportion of reconstructed breast | Z42.1Encounter for breast reconstruction following mastectomy | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | N00-N99 — Diseases of the Genitourinary System (N00-N99) | Z00-Z99 — Factors Influencing Health Status and Contact with Health Services (Z00-Z99) |
| Definition | Disproportion of reconstructed breast is a billable ICD-10-CM diagnosis code (N65.1). | Encounter for breast reconstruction following mastectomy is a billable ICD-10-CM diagnosis code (Z42.1). |
| Includes | Breast asymmetry between native breast and reconstructed breast Disproportion between native breast and reconstructed breast | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources