ICD-10 Code C84.Z0 – Other mature T/NK-cell lymphomas, unspecified site (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C84.Z0 – Other mature T/NK-cell lymphomas, unspecified site
What it is
This code identifies mature T-cell or natural killer cell lymphoma when the record does not specify the anatomic site. Use it for a documented lymphoma diagnosis that fits this category but lacks site detail.
Clinical signs
Clinical features vary; refer to documentation. Common lymphoma findings may include enlarged lymph nodes, systemic “B” symptoms, or extranodal disease, but you should code only what is explicitly documented.
When to use this code
Use C84.Z0 when the provider documents other mature T/NK-cell lymphoma and does not identify a primary site. It is appropriate when the site is unavailable in the chart or not stated in the final diagnosis.
Choose this code only after reviewing the note, pathology, and discharge summary for a more specific site or subtype. If the record identifies a site, code that specific option instead of the unspecified-site code.
Do not use for
Do not use this code for B-cell lymphomas, leukemias, or lymphomas with a clearly documented site. Check documentation if the subtype or anatomic location is named elsewhere.
Coding tip
Query the provider when “other mature T/NK-cell lymphoma” is documented without site detail and a more specific diagnosis may be supported.