ICD-10 Code A31.1 – Cutaneous mycobacterial infection (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A31.1 – Cutaneous mycobacterial infection
What it is
A31.1 identifies a skin infection caused by nontuberculous mycobacteria. Use it when the record documents a cutaneous mycobacterial infection rather than a deeper or pulmonary mycobacterial disease.
Clinical signs
Typical findings include chronic skin lesions, nodules, ulcers, abscesses, or draining sinuses. Clinical features vary; refer to documentation for the organism, site, and whether the infection is localized to the skin.
When to use this code
Use A31.1 when the provider clearly documents cutaneous mycobacterial infection, including skin-only disease due to nontuberculous mycobacteria. It is appropriate when the diagnosis is confirmed clinically, by culture, pathology, or other documented evidence.
Choose this code for infections described as cutaneous, skin, or dermatologic mycobacterial involvement. If the note is unclear about the site or organism, check documentation before assigning the code.
Do not use for
Do not use this code for tuberculosis of the skin, generalized mycobacterial infection, or infections limited to other organs. Check documentation if the record only says “mycobacterial infection” without a skin site.
Coding tip
Verify that the provider links the infection to the skin; if the site is not explicit, query for clarification before coding A31.1.