C00.0 vs C4A.0
C00.0 (Malignant neoplasm of external upper lip) compared with C4A.0 (Merkel cell carcinoma of lip), 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. C00.0 carries an Excludes1 note covering C4A.0: “Merkel cell carcinoma of lip (C4A.0)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
No — do not report together. C4A.0 carries an Excludes1 note covering C00.0: “malignant neoplasm of vermilion border of lip (C00.0-C00.2)”
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
| C00.0Malignant neoplasm of external upper lip | C4A.0Merkel cell carcinoma of lip | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | C00-D49 — Neoplasms (C00-D49) | C00-D49 — Neoplasms (C00-D49) |
| Definition | Malignant neoplasm of external upper lip is a billable ICD-10-CM diagnosis code (C00.0). | Merkel cell carcinoma of lip is a billable ICD-10-CM diagnosis code (C4A.0). |
| Includes | Malignant neoplasm of lipstick area of upper lip Malignant neoplasm of upper lip NOS Malignant neoplasm of vermilion border of upper lip | — |
| Use additional code | code to identify: alcohol abuse and dependence (F10.-) history of tobacco dependence (Z87.891) | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources