ICD-10 Code C85.29 – Mediastinal (thymic) large B-cell lymphoma, extranodal and solid organ sites (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C85.29 – Mediastinal (thymic) large B-cell lymphoma, extranodal and solid organ sites
What it is
This code identifies mediastinal (thymic) large B-cell lymphoma involving extranodal or solid organ sites. Use it for documentation that specifically names this lymphoma type and site.
Clinical signs
Clinical features vary; refer to documentation. Commonly, records may describe a mediastinal mass, chest pressure, cough, or other findings consistent with lymphoma involvement.
When to use this code
Use C85.29 when the provider documents mediastinal (thymic) large B-cell lymphoma affecting extranodal or solid organ sites. It is appropriate when the diagnosis is confirmed or clearly stated in the chart. If the site or lymphoma type is not specified, check documentation before coding.
Do not use for
Do not use this code for other non-Hodgkin lymphomas, unspecified lymphoma, or disease limited to lymph nodes without the documented mediastinal thymic subtype. Check documentation if the site is unclear.
Coding tip
Match the exact lymphoma subtype and site wording in the provider record before assigning C85.29.