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ICD-10-CM 2027 diagnosis code

A18.4Tuberculosis of skin and subcutaneous tissue

✓ Billable / specificCC — complication/comorbidity

A18.4 is a valid, billable ICD-10-CM code for tuberculosis of skin and subcutaneous tissue. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Looking up by condition? See ICD-10 code for Acnitis, ICD-10 code for Scrofulide, ICD-10 code for Tuberculid, ICD-10 code for Scrofuloderma.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About A18.4

A18.4 is the ICD-10-CM diagnosis code for tuberculosis of skin and subcutaneous tissue. It belongs to category A18 (tuberculosis of other organs), block A15-A19 (tuberculosis) and chapter 1 (certain infectious and parasitic diseases). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within A18 (tuberculosis of other organs), A18.4 is specifically for tuberculosis of skin and subcutaneous tissue. Related codes cover tuberculosis of bones and joints (A18.0), tuberculosis of genitourinary system (A18.1), tuberculous peripheral lymphadenopathy (A18.2), tuberculosis of intestines, peritoneum and mesenteric glands (A18.3), tuberculosis of eye (A18.5), tuberculosis of (inner) (middle) ear (A18.6), tuberculosis of adrenal glands (A18.7) and tuberculosis of other specified organs (A18.8).

The conditions in its Excludes2 note aren't part of A18.4, but may be coded alongside it if the patient has both: lupus erythematosus (L93.-) and systemic lupus erythematosus (M32.-).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 606 (Minor Skin Disorders with MCC, relative weight 1.5728), DRG 607 (Minor Skin Disorders without MCC, relative weight 0.8772), DRG 974 (HIV with Major Related Condition with MCC, relative weight 3.0506), DRG 975 (HIV with Major Related Condition with CC, relative weight 1.3252) and DRG 976 (HIV with Major Related Condition without CC/MCC, relative weight 0.8124), in MDC 09 (Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast) and MDC 25 (Human Immunodeficiency Virus Infections), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 017.00 (tuberculosis of skin and subcutaneous cellular tissue, unspecified) and 017.10 (erythema nodosum with hypersensitivity reaction in tuberculosis, unspecified).

Coding notes

Applicable toConditions and synonyms classified to this code
  • Erythema induratum, tuberculous
  • Lupus exedens
  • Lupus vulgaris NOS
  • Lupus vulgaris of eyelid
  • Scrofuloderma
  • Tuberculosis of external ear
Excludes2Not included here — may be reported together if both conditions exist
  • lupus erythematosus (L93.-)
  • systemic lupus erythematosus (M32.-)

Notes that apply from higher levels

Instructions written at a parent level also apply to A18.4.

Broader instructions also apply from A15-A19 Tuberculosis and Chapter 1: Certain infectious and parasitic diseases.

Alphabetic index entries

40 entries

Terms in the official ICD-10-CM index that lead to A18.4.

Codes whose notes reference A18.4

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

MDC 09 · Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast

ICD-9-CM equivalent

Converter →
  • 017.00Tuberculosis of skin and subcutaneous cellular tissue, unspecifiedapproximate
  • 017.10Erythema nodosum with hypersensitivity reaction in tuberculosis, unspecifiedapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about A18.4

Is A18.4 billable?

Yes. A18.4 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can A18.4 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict A18.4 as a principal diagnosis.

Is A18.4 a CC or MCC?

A18.4 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does A18.4 group to?

A18.4 is used in the MS-DRG v44.0 logic for MS-DRG 606 (Minor Skin Disorders with MCC), MS-DRG 607 (Minor Skin Disorders without MCC), MS-DRG 974 (HIV with Major Related Condition with MCC), MS-DRG 975 (HIV with Major Related Condition with CC) and MS-DRG 976 (HIV with Major Related Condition without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for A18.4?

The CMS General Equivalence Mappings map A18.4 to ICD-9-CM 017.00 and 017.10.