ICD-10 Code C84.4 – Peripheral T-cell lymphoma, not elsewhere classified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C84.4 – Peripheral T-cell lymphoma, not elsewhere classified
What it is
C84.4 identifies a peripheral T-cell lymphoma that does not fit a more specific subtype. Use it for a mature T-cell non-Hodgkin lymphoma when the record states “not elsewhere classified” or equivalent wording.
Clinical signs
Clinical features vary; refer to documentation. Common findings in peripheral T-cell lymphoma include enlarged lymph nodes, systemic “B” symptoms, and extranodal involvement, but you should code only what is documented.
When to use this code
Use C84.4 when the provider documents peripheral T-cell lymphoma, NOS, or peripheral T-cell lymphoma not elsewhere classified. It is appropriate when the pathology or oncology note confirms this specific lymphoma type and no more specific subtype is named. Check documentation if the diagnosis is uncertain or still being worked up.
Do not use for
Do not use this code for B-cell lymphomas, Hodgkin lymphoma, or cutaneous T-cell lymphoma unless the record specifically supports C84.4. If a more specific peripheral T-cell lymphoma subtype is documented, code that instead.
Coding tip
Code from the final pathology or oncology diagnosis, and query if the subtype is unclear or only “lymphoma” is documented.