ICD-10 Code L04.9 – Acute lymphadenitis, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code L04.9 – Acute lymphadenitis, unspecified
What it is
L04.9 identifies acute inflammation of lymph nodes when the affected site is not specified. Use it when the record documents acute lymphadenitis but does not name a particular node group.
Clinical signs
Typical findings include enlarged, tender lymph nodes with possible redness or warmth over the area. Clinical features vary; refer to documentation for the involved location and any associated infection.
When to use this code
Use L04.9 when the provider documents acute lymphadenitis and gives no more specific anatomic site. It also fits when the note confirms swollen, inflamed lymph nodes but does not identify cervical, axillary, or other nodes. If the record names a site, code the more specific option instead.
Do not use for
Do not use this code for chronic lymphadenitis, generalized lymph node enlargement, or lymphadenopathy without inflammation. Check documentation if the note describes a specific node region or a different underlying diagnosis.
Coding tip
Code the documented node location whenever possible; unspecified should be your fallback only when the chart lacks a clear site.