ICD-10 Code C82.42 – Follicular lymphoma grade IIIb, intrathoracic lymph nodes (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C82.42 – Follicular lymphoma grade IIIb, intrathoracic lymph nodes
What it is
This code identifies follicular lymphoma grade IIIb involving intrathoracic lymph nodes. It refers to a high-grade B-cell lymphoma localized to lymph nodes in the chest.
Clinical signs
Clinical features vary; refer to documentation. Commonly documented findings include enlarged intrathoracic lymph nodes on imaging and pathology confirming follicular lymphoma grade IIIb.
When to use this code
Use this code when the provider documents follicular lymphoma grade IIIb and specifies intrathoracic lymph node involvement. Apply it after biopsy or other definitive pathology supports the diagnosis.
Code it when the record clearly identifies mediastinal, hilar, or other intrathoracic nodes as the site. If the site or grade is unclear, check documentation before assigning the code.
Do not use for
Do not use this code for follicular lymphoma of another grade, unspecified lymphoma, or lymphoma at a different nodal site. Check documentation if the report does not confirm grade IIIb.
Coding tip
Verify both the histologic grade and the anatomic site in the pathology or provider note before coding.