ICD-10 Code C85.24 – Mediastinal (thymic) large B-cell lymphoma, lymph nodes of axilla and upper limb (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C85.24 – Mediastinal (thymic) large B-cell lymphoma, lymph nodes of axilla and upper limb
What it is
This code identifies mediastinal (thymic) large B-cell lymphoma involving lymph nodes of the axilla and upper limb. Use it for this specific lymphoma site and nodal location, not for other non-Hodgkin lymphomas.
Clinical signs
Clinical features vary; refer to documentation. Commonly, records describe a mediastinal mass or enlarged axillary or upper-limb lymph nodes, with tissue diagnosis confirming large B-cell lymphoma.
When to use this code
Use C85.24 when the provider documents mediastinal (thymic) large B-cell lymphoma and specifies involvement of axillary or upper-limb lymph nodes. Code from pathology, oncology, or discharge documentation that clearly links the lymphoma subtype and site.
If the record only says lymphoma or non-Hodgkin lymphoma without this exact site and histology, check documentation before coding. You should not assume the mediastinal subtype from imaging alone.
Do not use for
Do not use this code for other lymphomas, unspecified lymphoma, or lymph node enlargement without confirmed malignant lymphoma. Check documentation if the site is not axillary or upper limb.
Coding tip
Assign this code only when both the mediastinal (thymic) subtype and the axillary or upper-limb nodal site are documented together.