ICD-10 Code C84.42 – Peripheral T-cell lymphoma, not elsewhere classified, intrathoracic lymph nodes (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C84.42 – Peripheral T-cell lymphoma, not elsewhere classified, intrathoracic lymph nodes
What it is
This code identifies peripheral T-cell lymphoma, not otherwise specified, when the involved site is the intrathoracic lymph nodes. Use it for a documented T-cell non-Hodgkin lymphoma affecting lymph nodes inside the chest.
Clinical signs
Clinical features vary; refer to documentation. Common findings may include enlarged intrathoracic lymph nodes on imaging and symptoms related to chest involvement, but you should code only when the record confirms the diagnosis and site.
When to use this code
Use this code when the provider documents peripheral T-cell lymphoma, not elsewhere classified, with intrathoracic lymph node involvement. It is appropriate for confirmed lymphoma cases where the chest nodes are the specified primary site or involved site. If the site is unclear, check documentation before coding.
Do not use for
Do not use it for other lymphoma subtypes, unspecified lymphoma, or lymph node disease outside the thorax. If the record does not clearly state peripheral T-cell lymphoma and intrathoracic lymph node involvement, check documentation.
Coding tip
Match both the lymphoma type and the anatomic site exactly; if either is missing, query the provider.