ICD-10 Code C84.1 – Sézary disease (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C84.1 – Sézary disease
What it is
C84.1 identifies Sézary disease, a leukemic form of cutaneous T-cell lymphoma. It is a malignant T-cell disorder that primarily affects the skin and may involve blood and lymph nodes.
Clinical signs
Typical findings include widespread redness and scaling of the skin, severe itching, and enlarged lymph nodes. Clinical features vary; refer to documentation.
When to use this code
Use C84.1 when the provider documents Sézary disease or Sézary syndrome as the confirmed diagnosis. Apply it for encounters focused on evaluation, monitoring, or management of this specific T-cell lymphoma. Check documentation if the record only says cutaneous lymphoma or erythroderma.
Do not use for
Do not use this code for nonspecific dermatitis, eczema, or other skin eruptions without a documented Sézary diagnosis. Avoid it when the note describes another lymphoma subtype.
Coding tip
Code only when the provider clearly documents Sézary disease; otherwise, query for the exact lymphoma type.