ICD-10 Code C84.03 – Mycosis fungoides, intra-abdominal lymph nodes (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C84.03 – Mycosis fungoides, intra-abdominal lymph nodes
What it is
This code identifies mycosis fungoides, a cutaneous T-cell lymphoma, when it involves intra-abdominal lymph nodes. Use it for documented nodal disease in the abdomen, not for skin-only involvement.
Clinical signs
Clinical features vary; refer to documentation. Findings may include enlarged intra-abdominal lymph nodes and evidence of lymphoma spread from mycosis fungoides, usually supported by pathology, imaging, or specialist assessment.
When to use this code
Use this code when the provider clearly documents mycosis fungoides affecting intra-abdominal lymph nodes. It is appropriate when the record specifies abdominal nodal involvement, even if the skin disease is also present. Check documentation if the note only says lymphadenopathy or lymphoma without site detail.
Do not use for
Do not use this code for mycosis fungoides limited to skin or to other lymph node regions. Do not assign it when the abdominal nodal site is not documented.
Coding tip
Verify the exact nodal location in the oncology note or pathology report before assigning C84.03.