ICD-10 Code C84.Z – Other mature T/NK-cell lymphomas (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C84.Z – Other mature T/NK-cell lymphomas
What it is
C84.Z identifies mature T-cell or natural killer (NK)-cell lymphomas that do not fit a more specific ICD-10-CM subtype. Use it for documented “other” mature T/NK-cell lymphoma diagnoses when the record does not name a finer category.
Clinical signs
Clinical features vary; refer to documentation. These lymphomas may present with lymphadenopathy, skin lesions, systemic “B” symptoms, or extranodal disease, depending on the subtype and site involved.
When to use this code
Use C84.Z when the provider documents an other mature T/NK-cell lymphoma and the chart does not support a more specific code. It is appropriate when pathology or oncology notes confirm a mature T- or NK-cell lymphoma, but the exact subtype is unspecified or grouped as other. Check documentation for the precise wording.
Do not use for
Do not use this code for B-cell lymphomas, Hodgkin lymphoma, or immature lymphoid neoplasms. If a specific mature T/NK-cell lymphoma subtype is documented, code that diagnosis instead.
Coding tip
Match the code to the exact pathology or oncology term and code the most specific lymphoma diagnosis available.