Is A50.42 a billable ICD-10-CM code?

Yes. A50.42 is a billable, specific ICD-10-CM code and is valid for submission on a claim.

Where does A50.42 sit in the tabular list?

Certain infectious and parasitic diseases (A00-B99), in the block Infections with a predominantly sexual mode of transmission (A50-A64).

What cannot be coded together with A50.42?

A50.42 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above A50.42 (A50.4) and apply to it just the same.

A50.42

A50.42 — Late congenital syphilitic encephalitis

Billable / specific codeICD-10-CM

A50.42 is a billable, specific ICD-10-CM code for late congenital syphilitic encephalitis. It is valid for submission on a claim.

Excludes1 inherited from the categories above A50.42

These are not written on A50.42, but they bind it: a note on a category applies to every code beneath it. Billing A50.42 with anything listed here is a denial.

Written on A50.4 — Late congenital neurosyphilis [juvenile neurosyphilis]

Hutchinson's triad (A50.53)

Risk adjustment

A50.42 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Medicare coverage

A50.42 is named in 8 Medicare coverage policies — 8 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

A52996Billing and Coding: Routine Foot Care
A56771Billing and Coding: Special Electroencephalography
A56937Billing and Coding: Psychiatry and Psychology Services
A57065Billing and Coding: Outpatient Psychiatry and Psychology Services

How A50.42 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 A50.42.

Encephalitis›in›syphilis›congenital

Code history

A50.42 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.

Related codes at this level

Codes that share A50.4. If A50.42 is not quite right, the correct code is usually one of these.

Questions about A50.42

Is A50.42 a billable ICD-10-CM code?: Yes. A50.42 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does A50.42 sit in the tabular list?: Certain infectious and parasitic diseases (A00-B99), in the block Infections with a predominantly sexual mode of transmission (A50-A64).
What cannot be coded together with A50.42?: A50.42 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above A50.42 (A50.4) and apply to it just the same.