ICD-10 Code C84.01 – Mycosis fungoides, lymph nodes of head, face, and neck (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C84.01 – Mycosis fungoides, lymph nodes of head, face, and neck
What it is
This code identifies mycosis fungoides involving the lymph nodes of the head, face, or neck. It reflects a cutaneous T-cell lymphoma with regional nodal involvement in that anatomic area.
Clinical signs
Findings may include persistent skin lesions with enlarged regional lymph nodes in the head, face, or neck. Clinical features vary; refer to documentation for confirmed nodal involvement and disease extent.
When to use this code
Use this code when the provider documents mycosis fungoides with lymph node involvement limited to the head, face, or neck. It may be supported by pathology, imaging, or a clear specialist assessment. If the record does not specify the nodal site, check documentation.
Do not use for
Do not use this code for mycosis fungoides without documented nodal involvement, or when nodes from another region are specified. Check documentation if the diagnosis is uncertain or the location is not stated.
Coding tip
Code the exact lymph node region documented; site specificity matters for C84.01.