ICD-10 Code C84 – Mature T/NK-cell lymphomas (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C84 – Mature T/NK-cell lymphomas
What it is
C84 identifies mature T-cell and natural killer (NK)-cell lymphomas, a group of cancers arising from lymphocytes. Use it when documentation names this lymphoma category without a more specific subtype.
Clinical signs
Clinical features vary; refer to documentation. Commonly reported findings include lymphadenopathy, skin involvement, systemic symptoms, or extranodal disease, depending on the specific subtype.
When to use this code
Use C84 when the provider documents mature T-cell lymphoma, NK-cell lymphoma, or mature T/NK-cell lymphoma and no narrower ICD-10-CM code is specified. It is also appropriate when the record confirms this broad category but does not identify the exact histology or site. Check documentation if the subtype is named.
Do not use for
Do not use this code for B-cell lymphomas, Hodgkin lymphoma, or leukemias. If the chart identifies a more specific mature T/NK-cell lymphoma subtype, code that diagnosis instead.
Coding tip
Review pathology and oncology notes carefully; a more specific subtype within C84 may be available and should be reported when documented.