C44 vs C51

C44 (Other and unspecified malignant neoplasm of skin) compared with C51 (Malignant neoplasm of vulva), 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. C44 carries an Excludes1 note covering C51: “malignant neoplasm of skin of genital organs (C51-C52, C60.-, C63.2)”

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

	C44Other and unspecified malignant neoplasm of skin	C51Malignant neoplasm of vulva
Billing status	Non-billable header Report instead: C44.00, C44.01, C44.02, C44.09, C44.101	Non-billable header Report instead: C51.0, C51.1, C51.2, C51.8, C51.9
Classification	C00-D49 — Neoplasms (C00-D49)	C00-D49 — Neoplasms (C00-D49)
Definition	Other and unspecified malignant neoplasm of skin is a non-billable ICD-10-CM category code (C44).	Malignant neoplasm of vulva is a non-billable ICD-10-CM category code (C51).
Includes	malignant neoplasm of sebaceous glands malignant neoplasm of sweat glands	malignant neoplasm of skin of female genital organs

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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources