A18.4 — Tuberculosis of skin and subcutaneous tissue
A18.4 is a billable, specific ICD-10-CM code for tuberculosis of skin and subcutaneous tissue. It is valid for submission on a claim.
Excludes2 — not included here, but may coexist
The excluded condition is not part of this code, but a patient can have both. You may code both.
Inclusion terms
Alternative wordings a physician may use in the chart for this same code.
- Erythema induratum, tuberculous
- Lupus exedens
- Lupus vulgaris NOS
- Lupus vulgaris of eyelid
- Scrofuloderma
- Tuberculosis of external ear
Other codes that can never be billed with A18.4
These codes carry an Excludes1 note pointing at A18.4. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading A18.4 alone.
Risk adjustment
A18.4 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
A18.4 is named in 11 Medicare coverage policies — 11 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A56416Billing and Coding: Assays for Vitamins and Metabolic Function
- A56841Billing and Coding: Vitamin D; 25 hydroxy, includes fraction(s), if performed
- A57484Billing and Coding: Vitamin D Assay Testing
- A57484Billing and Coding: Vitamin D Assay Testing
How A18.4 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 A18.4.
- Acnitis(primary)
- Bazin's disease(primary) (tuberculous)
- Lichenoides tuberculosis(primary)
- Scrofulide(primary) (tuberculous)
- Scrofuloderma, scrofulodermia(any site) (primary)
- Scrofulosus lichen(primary) (tuberculous)
- Tuberculid, tuberculide(indurating, subcutaneous) (lichenoid) (miliary) (papulonecrotic) (primary) (skin)
- Cellulitis›tuberculous(primary)
- Erythema, erythematous›tuberculous(primary)
- Gumma›scrofulous(tuberculous)
- Gumma›tuberculous
- Lichen›scrofulosus(primary) (tuberculous)
Related codes at this level
Codes that share A18. If A18.4 is not quite right, the correct code is usually one of these.
- A18.0Tuberculosis of bones and joints
- A18.1Tuberculosis of genitourinary system
- A18.2Tuberculous peripheral lymphadenopathy
- A18.3Tuberculosis of intestines, peritoneum and mesenteric glands
- A18.5Tuberculosis of eye
- A18.6Tuberculosis of (inner) (middle) ear
- A18.7Tuberculosis of adrenal glands
- A18.8Tuberculosis of other specified organs
Questions about A18.4
- Is A18.4 a billable ICD-10-CM code?
- Yes. A18.4 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does A18.4 sit in the tabular list?
- Certain infectious and parasitic diseases (A00-B99), in the block Tuberculosis (A15-A19).