ICD-10 Code C85.18 – Unspecified B-cell lymphoma, lymph nodes of multiple sites (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C85.18 – Unspecified B-cell lymphoma, lymph nodes of multiple sites
What it is
C85.18 identifies a B-cell lymphoma involving lymph nodes at more than one site, when the subtype is not further specified. Use it when documentation confirms B-cell lymphoma but does not name a more precise histology.
Clinical signs
Clinical features vary; refer to documentation. Common findings may include enlarged lymph nodes in multiple regions, but the record should support lymphoma involvement and the multi-site nodal pattern.
When to use this code
Use this code when the provider documents unspecified B-cell lymphoma affecting lymph nodes of multiple sites and no more specific lymphoma type is recorded. It may apply at initial diagnosis, on referral, or when pathology is incomplete. If the chart later identifies a specific subtype, code the more specific diagnosis instead.
Do not use for
Do not use this code for a specified B-cell lymphoma subtype or for lymphoma limited to one lymph node site. Check documentation if the record describes non-Hodgkin lymphoma without confirming B-cell origin.
Coding tip
Verify both the cell type and the multi-site nodal involvement before assigning C85.18.