ICD-10 Code C84.18 – Sézary disease, lymph nodes of multiple sites (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C84.18 – Sézary disease, lymph nodes of multiple sites
What it is
C84.18 identifies Sézary disease involving lymph nodes at multiple sites. Use it when the record documents this cutaneous T-cell lymphoma with nodal involvement beyond a single location.
Clinical signs
Typical findings include generalized skin redness, itching, and lymphadenopathy. Clinical features vary; refer to documentation for confirmed Sézary disease and the extent of nodal involvement.
When to use this code
Use C84.18 when the provider specifically documents Sézary disease and states that lymph nodes at multiple sites are involved. It may also apply when pathology or oncology notes clearly confirm multi-site nodal disease. If the record only says lymphoma or skin disease without this specificity, check documentation.
Do not use for
Do not use this code for mycosis fungoides, other cutaneous lymphomas, or isolated skin disease without documented nodal spread. If the lymph node sites are not specified, check documentation.
Coding tip
Match the code to the exact anatomic extent documented; “multiple sites” must be explicit in the chart.