ICD-10 Code C84.Z9 – Other mature T/NK-cell lymphomas, extranodal and solid organ sites (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C84.Z9 – Other mature T/NK-cell lymphomas, extranodal and solid organ sites
What it is
This code identifies a mature T-cell or NK-cell lymphoma that is located in an extranodal or solid organ site. Use it when the record specifies this lymphoma category but does not name a more specific subtype.
Clinical signs
Clinical features vary; refer to documentation. Findings may reflect a mass or infiltrative lesion in a non-lymph node organ, with pathology confirming a mature T/NK-cell lymphoma.
When to use this code
Use this code when the provider documents an other mature T/NK-cell lymphoma involving an extranodal site or solid organ, and no more specific code is available. It may apply after biopsy or pathology report review. If the site or lymphoma subtype is unclear, check documentation.
Do not use for
Do not use it for nodal lymphomas, B-cell lymphomas, or a more specific mature T/NK-cell lymphoma code. Check documentation if the record only says “lymphoma” without confirming the cell type and site.
Coding tip
Match both the lymphoma type and the extranodal or solid organ site in the pathology or oncology note before assigning C84.Z9.