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ICD10BillableValid for clinical use

ICD-10 Code A18.4: Tuberculosis of skin and subcutaneous tissue

A18.4 is a billable ICD-10 diagnosis code used to classify Tuberculosis of skin and subcutaneous tissue in medical records and claims. You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records. ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Certain infectious and parasitic diseases (A00-B99).

What is this code?

ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Certain infectious and parasitic diseases (A00-B99).

đź“‹Clinical overview

This ICD-10 code is commonly used when documentation describes extrapulmonary tuberculosis affecting bones, joints, genitourinary organs, lymph nodes, abdominal structures, skin, eye, ear, endocrine organs, heart, spleen, or other named sites. The most accurate code depends on the documented organ site and whether the chart names a more specific anatomic location.

When is it used?

  • May be used when a clinician documents tuberculosis of skin and subcutaneous tissue in a patient's medical record.
  • May appear in hospital records, claims, referrals, and clinical documentation.
  • This code can be used as a clinically usable diagnosis entry in standardized coding workflows.

What it does not mean

  • A code alone does not explain severity, treatment plan, or outcome.
  • A medical code should not be treated as a substitute for a doctor's diagnosis or advice.

đź©şClinical context

When commonly used
  • Infectious-disease, inpatient, specialty, and follow-up documentation where tuberculosis is documented outside the lungs and the affected organ system changes code specificity.
  • Coding and utilization-review workflows where the chart clearly identifies extrapulmonary tuberculosis involving bone, genitourinary organs, lymph nodes, abdomen, skin, eye, ear, endocrine organs, heart, spleen, or another named site.
Common management context
  • Extrapulmonary-tuberculosis follow-up often includes microbiology, pathology, imaging, organ-specific monitoring, and infectious-disease treatment planning based on the affected site.
  • Documentation usually becomes more specific when the chart identifies the exact organ, structure, or body system involved rather than using a broader 'other organs' tuberculosis label.
  • Specialist context already linked on this page includes Infectious Disease Specialist, General Physician, Dermatologist.

🔍Key distinctions

Important notes
  • This ICD-10 family covers extrapulmonary or other-organ tuberculosis and is distinct from pulmonary tuberculosis branches because the affected organ site drives code selection.
  • Specific anatomic-site detail matters here, because spine, kidney, bladder, thyroid, adrenal, heart, spleen, skin, eye, ear, and other named organ involvement are coded separately when documented.
  • Cutaneous, ocular, and ear tuberculosis are coded separately from other organ-site tuberculosis branches because the documented body site changes the final code.
Important exclusions
  • lupus erythematosus (L93.-)
  • systemic lupus erythematosus (M32.-)
Related codes to consider
A18.0Tuberculosis of bones and joints
Related extrapulmonary-tuberculosis ICD-10 code; documentation often becomes more specific when the chart identifies the affected organ system or names a more precise anatomic site.
A18.1Tuberculosis of genitourinary system
Related extrapulmonary-tuberculosis ICD-10 code; documentation often becomes more specific when the chart identifies the affected organ system or names a more precise anatomic site.
A18.2Tuberculous peripheral lymphadenopathy
Related extrapulmonary-tuberculosis ICD-10 code; documentation often becomes more specific when the chart identifies the affected organ system or names a more precise anatomic site.
A18.3Tuberculosis of intestines, peritoneum and mesenteric glands
Related extrapulmonary-tuberculosis ICD-10 code; documentation often becomes more specific when the chart identifies the affected organ system or names a more precise anatomic site.

Code hierarchy

chapter
1Certain infectious and parasitic diseases (A00-B99)
block
A15-A19Tuberculosis
category
A18Tuberculosis of other organs
currentA18

Official coding notes

Inclusion terms
  • Erythema induratum, tuberculous
  • Lupus exedens
  • Lupus vulgaris NOS
  • Lupus vulgaris of eyelid
  • Scrofuloderma
  • Tuberculosis of external ear
Excludes2 (may code together if documented)
  • lupus erythematosus (L93.-)
  • systemic lupus erythematosus (M32.-)

Where you may see this code

You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.

Related specialists

Infectious Disease SpecialistGeneral PhysicianDermatologist

Coding guidelines

Compatibility

Legacy and official ICD code match exactly.
Legacy codes
A18.4

Common synonyms

Tuberculosis of skin and subcutaneous tissue

Frequently asked questions

Code details

CodeA18.4
SystemICD10
Display nameTuberculosis of skin and subcutaneous tissue
ChapterCertain infectious and parasitic diseases (A00-B99)
BlockTuberculosis

Flags

BillableYes
Valid clinical useYes

Source

SourceICD-10
Version2026-annual
Releaseannual
Year2026

Index terms

Matched terms
Acnitis(primary)Bazin's disease(primary) (tuberculous)Cellulitis(diffuse) (phlegmonous) (septic) (suppurative)Erythema, erythematous(infectional) (inflammation)Erythema, erythematous(infectional) (inflammation)Erythema, erythematous(infectional) (inflammation)Gumma(syphilitic)Gumma(syphilitic)LichenLichenoides tuberculosis(primary)LupusLupus

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.