ICD-10 Code C84.Z1 – Other mature T/NK-cell lymphomas, lymph nodes of head, face, and neck (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C84.Z1 – Other mature T/NK-cell lymphomas, lymph nodes of head, face, and neck
What it is
This code identifies a mature T-cell or NK-cell lymphoma involving lymph nodes in the head, face, or neck. Use it when the record specifies this lymphoma type and nodal location.
Clinical signs
Findings may include enlarged cervical or facial lymph nodes, persistent swelling, or other lymphoma-related symptoms. Clinical features vary; refer to documentation.
When to use this code
Use this code when the provider documents an other mature T/NK-cell lymphoma and clearly states the affected lymph nodes are in the head, face, or neck. It is appropriate for confirmed primary nodal disease in that anatomic region. Check documentation if the site is described only generally.
Do not use for
Do not use this code for unspecified lymphoma histology, nodal disease outside the head, face, or neck, or non-lymphoma masses. If the chart does not confirm both the cell type and site, check documentation.
Coding tip
Code the histology and the exact nodal location together; if either element is missing, query the provider.