ICD-10 Code C84.Z4 – Other mature T/NK-cell lymphomas, lymph nodes of axilla and upper limb (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C84.Z4 – Other mature T/NK-cell lymphomas, lymph nodes of axilla and upper limb
What it is
This code identifies a mature T-cell or NK-cell lymphoma involving lymph nodes in the axilla or upper limb. It is used when the record specifies this anatomic site and the lymphoma type is not otherwise classified.
Clinical signs
Findings usually reflect lymph node lymphoma, such as enlarged nodes in the armpit or upper arm region. Clinical features vary; refer to documentation for the confirmed histology and site.
When to use this code
Use this code when the provider documents a mature T/NK-cell lymphoma affecting axillary or upper-limb lymph nodes and no more specific code applies. You should match the documented lymphoma subtype and location exactly. Check documentation if the site is described only broadly.
Do not use for
Do not use it for lymphomas with a different cell lineage, a different nodal region, or a more specific coded diagnosis. Do not assign it when the record does not clearly identify axillary or upper-limb lymph node involvement.
Coding tip
Verify both the lymphoma category and the nodal site in the pathology or oncology note before coding.