ICD-10 Code C83.99 – Non-follicular (diffuse) lymphoma, unspecified, extranodal and solid organ sites (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C83.99 – Non-follicular (diffuse) lymphoma, unspecified, extranodal and solid organ sites
What it is
This code identifies a diffuse, non-follicular lymphoma found in an extranodal location or a solid organ, when the exact subtype is not documented. Use it when the record confirms lymphoma but does not specify a more precise histology.
Clinical signs
Clinical features vary; refer to documentation. Patients may have a mass, organ enlargement, or symptoms related to the involved extranodal site, but the record should support the lymphoma diagnosis and location.
When to use this code
Use C83.99 when the provider documents non-follicular lymphoma involving an extranodal site or solid organ and does not identify a more specific codeable subtype. It is also appropriate when pathology or oncology notes confirm lymphoma, but the exact classification remains unspecified. Check documentation for the site and histology.
Do not use for
Do not use this code for follicular lymphoma, nodal lymphoma, or a more specific diffuse lymphoma code when documented. If the pathology or clinician names a different subtype or site, code that condition instead.
Coding tip
Before assigning C83.99, verify both the extranodal or solid organ site and that no more specific lymphoma subtype is documented.