ICD-10 Code C83.90 – Non-follicular (diffuse) lymphoma, unspecified, unspecified site (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C83.90 – Non-follicular (diffuse) lymphoma, unspecified, unspecified site
What it is
C83.90 identifies a non-follicular, or diffuse, lymphoma when the record does not specify the exact subtype or body site. Use it for a lymphoma diagnosis that is documented, but not further classified.
Clinical signs
Clinical features vary; refer to documentation. Commonly, lymphoma may present with lymph node enlargement, constitutional symptoms, or disease found on imaging or biopsy, but the exact findings must be recorded in the chart.
When to use this code
Use this code when the provider documents non-follicular or diffuse lymphoma and does not name a more specific lymphoma type or site. It also fits when the site is unspecified in the available record. If pathology or later notes identify a more precise diagnosis, code that instead.
Do not use for
Do not use C83.90 when the record specifies a follicular lymphoma, a different lymphoma subtype, or a definite anatomic site. Check documentation if the pathology report or oncology note gives a more detailed diagnosis.
Coding tip
Before assigning C83.90, confirm that both the subtype and site remain unspecified in the final provider documentation.