ICD-10 Code C83.9 – Non-follicular (diffuse) lymphoma, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C83.9 – Non-follicular (diffuse) lymphoma, unspecified
What it is
C83.9 identifies a non-follicular, or diffuse, lymphoma when the record does not specify the exact subtype. Use it for a malignant lymphoid neoplasm documented as diffuse lymphoma without further detail.
Clinical signs
Clinical features vary; refer to documentation. Common lymphoma findings may include enlarged lymph nodes, unexplained weight loss, fever, night sweats, or fatigue, but you should code only what is documented.
When to use this code
Use C83.9 when the provider confirms non-follicular lymphoma but does not name a more specific subtype. It also fits when pathology or oncology notes state diffuse lymphoma and no additional classification is available. If later documentation identifies a specific lymphoma type, update the code.
Do not use for
Do not use this code for follicular lymphoma, Hodgkin lymphoma, or a clearly named non-follicular subtype. Check documentation if the report gives a more specific diagnosis or indicates lymphoma in remission.
Coding tip
Query for the exact histology and site when the chart says only “lymphoma,” because a more specific ICD-10 code may be available.