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A18.4 vs M32

A18.4 (Tuberculosis of skin and subcutaneous tissue) compared with M32 (Systemic lupus erythematosus (SLE)), from the official CMS tabular data.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Summary

These codes can be reported together when both conditions are documented, because A18.4 lists M32 under Excludes2, which marks them as distinct conditions.

Official rule
What is different?

The conditions named, billing status and chapter.A18.4 is “Tuberculosis of skin and subcutaneous tissue”; M32 is “Systemic lupus erythematosus (SLE)”. M32 is a non-billable header; A18.4 is billable. A18.4 sits in A00-B99 — Certain Infectious and Parasitic Diseases (A00-B99); M32 in M00-M99 — Diseases of the Musculoskeletal System and Connective Tissue (M00-M99).

Registry fact

Can these codes be reported together?

Yes, when both are documented.A18.4 lists M32 under Excludes2: “systemic lupus erythematosus (M32.-)”. Excludes2 marks distinct conditions that may both be reported when both are documented.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes1 relationship?

None.Neither entry carries an Excludes1 note that names the other code. A18.4 carries 7 Excludes1 notes and M32 carries 2 Excludes1 notes covering other codes; the side-by-side table quotes them.

Official rule

Is there an Excludes2 relationship?

Yes.A18.4’s tabular entry: “systemic lupus erythematosus (M32.-)”. The note covers M32.

Official ruleGuide: Excludes1 vs Excludes2

Is one more specific?

Not comparable.The codes sit in different categories; specificity is only comparable within one category.

Is one a parent or header code?

One is a header.M32 is a non-billable header, but A18.4 is not one of its subdivisions.

Registry fact

Are there sequencing instructions?

None.Neither entry carries a Code First or Use Additional Code note that names the other.

Official rule

Are there other coding relationships?

None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.

MedCoder-derived

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels

Can these codes be reported together?

Informational

Excludes2 relationship

A18.4
Tuberculosis of skin and subcutaneous tissue
↔
M32
Systemic lupus erythematosus (SLE)

What we found

Yes, when both are documented.A18.4 carries an Excludes2 note covering M32: “systemic lupus erythematosus (M32.-)”

Excludes2 marks distinct conditions — both may be reported when both are documented.

What to review

Report both only when the documentation supports both conditions; otherwise report the one documented.

Guide: Excludes1 vs Excludes2Check these on a claim

Why it matters

An Excludes2 note means the excluded condition is not part of the code above it, but a patient can have both. Report both when both are documented.

Source / rule

CMS ICD-10-CM tabular instructional notes

Official guidance behind these answers

  • Section I.A.12.b — Excludes2 · applies to: Excludes2

    A type 2 Excludes note represents “Not included here.” An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.

    ICD-10-CM Official Guidelines FY2027

Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum

Side by side

Similar descriptions do not make codes interchangeable. The documentation and the official instructions decide which code applies.

Official descriptionDiffers
A18.4

Tuberculosis of skin and subcutaneous tissue

M32

Systemic lupus erythematosus (SLE)

StatusDiffers
A18.4
Billable
M32
Non-billable header

A header is not reported on a claim; a code beneath it is.

Report instead: M32.0, M32.10, M32.11, M32.12, M32.13

Excludes1Differs
A18.4
  • congenital tuberculosis (P37.0)
  • nonspecific reaction to test for tuberculosis without active tuberculosis (R76.1-)
  • pneumoconiosis associated with tuberculosis, any type in A15 (J65)
  • positive PPD (R76.11)
  • positive tuberculin skin test without active tuberculosis (R76.11)
  • sequelae of tuberculosis (B90.-)
  • silicotuberculosis (J65)
M32
  • lupus erythematosus (discoid) (NOS) (L93.0)
  • autoimmune disease, single organ or single cell-type -code to relevant condition category
Excludes2Differs
A18.4
  • lupus erythematosus (L93.-)
  • systemic lupus erythematosus (M32.-)
M32

None at this code

Use additional codeDiffers
A18.4
  • code, if applicable, for associated cachexia (E88.A)
M32

None at this code

CategoryDiffers
A18.4

A18 Tuberculosis of other organs

M32

Is itself a category

ChapterDiffers
A18.4

A00-B99 — Certain Infectious and Parasitic Diseases (A00-B99)

M32

M00-M99 — Diseases of the Musculoskeletal System and Connective Tissue (M00-M99)

IncludesDiffers
A18.4
  • infections due to Mycobacterium tuberculosis and Mycobacterium bovis
  • Erythema induratum, tuberculous
  • Lupus exedens
  • Lupus vulgaris NOS
M32
  • autoimmune disease NOS
  • collagen (vascular) disease NOS
  • systemic autoimmune disease
  • systemic collagen (vascular) disease

No Code first, Code also and 7th character note at either code.

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on. In a row that differs, notes every code shares are dimmed.

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Derived from the official CMS ICD-10-CM tabular data (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources