Is C4A.0 a billable ICD-10-CM code?

Yes. C4A.0 is a billable, specific ICD-10-CM code and is valid for submission on a claim.

Where does C4A.0 sit in the tabular list?

Neoplasms (C00-D49), in the block Melanoma and other malignant neoplasms of skin (C43-C44).

What cannot be coded together with C4A.0?

C4A.0 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.

C4A.0

C4A.0 — Merkel cell carcinoma of lip

Billable / specific codeICD-10-CM

C4A.0 is a billable, specific ICD-10-CM code for merkel cell carcinoma of lip. It is valid for submission on a claim.

Excludes1 — never code together

These conditions cannot occur together. Billing both on the same encounter is a denial.

malignant neoplasm of vermilion border of lip (C00.0-C00.2)

Other codes that can never be billed with C4A.0

These codes carry an Excludes1 note pointing at C4A.0. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading C4A.0 alone.

C00Malignant neoplasm of lip

Risk adjustment

C4A.0 risk-adjusts. Under the CMS-HCC V28 model it maps to this category:

HCC 21 Lymphoma and Other Cancers0.671 RAF

Coefficient shown for the Community Non-dual Aged segment. A higher HCC in the same hierarchy will suppress this one, so capturing it does not always add score.

Medicare coverage

C4A.0 is named in 51 Medicare coverage policies — 51 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

A52479Oral Anticancer Drugs - Policy Article
A52479Oral Anticancer Drugs - Policy Article
A52479Oral Anticancer Drugs - Policy Article
A52480Oral Antiemetic Drugs (Replacement for Intravenous Antiemetics) - Policy Article

How C4A.0 is indexed

Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to C4A.0.

Carcinoma›Merkel cell›lip

Related codes at this level

Codes that share C4A. If C4A.0 is not quite right, the correct code is usually one of these.

Questions about C4A.0

Is C4A.0 a billable ICD-10-CM code?: Yes. C4A.0 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does C4A.0 sit in the tabular list?: Neoplasms (C00-D49), in the block Melanoma and other malignant neoplasms of skin (C43-C44).
What cannot be coded together with C4A.0?: C4A.0 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.