ICD-10 Code A18.4 – Tuberculosis of skin and subcutaneous tissue (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A18.4 – Tuberculosis of skin and subcutaneous tissue
What it is
A18.4 identifies tuberculosis infection involving the skin and the tissue beneath it. Use it when documentation shows cutaneous or subcutaneous TB, not a nonspecific skin infection.
Clinical signs
Clinical features vary; refer to documentation. Reported findings may include chronic skin lesions, nodules, ulcers, or draining areas with evidence of tuberculosis involvement.
When to use this code
Use A18.4 when the provider clearly documents tuberculosis affecting the skin or subcutaneous tissue. It may appear in a confirmed diagnosis, problem list, or discharge summary. If the record only says “skin lesion” or “abscess,” check documentation before assigning this code.
Do not use for
Do not use this code for ordinary bacterial skin infections, unspecified dermatitis, or skin findings without documented tuberculosis. If the site or cause is unclear, check documentation.
Coding tip
Code the TB site only when the record supports cutaneous involvement; otherwise, query for clarification rather than assuming extrapulmonary tuberculosis.