ICD-10 Code D89.84 – IgG4-related disease (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D89.84 – IgG4-related disease
What it is
D89.84 identifies IgG4-related disease, a systemic fibroinflammatory condition that can affect one or more organs. It is used when the record specifically documents this diagnosis.
Clinical signs
Clinical features vary; refer to documentation. Commonly reported findings include organ enlargement, mass-like lesions, and tissue fibrosis with IgG4-positive plasma cells on pathology.
When to use this code
Use D89.84 when the clinician documents IgG4-related disease, IgG4-RD, or a confirmed IgG4-related inflammatory process. Code it from the final diagnosis, problem list, or pathology-supported assessment. If the note only describes a suspected mass or nonspecific inflammation, check documentation before assigning this code.
Do not use for
Do not use this code for elevated IgG4 alone, nonspecific autoimmune disease, or organ swelling without a documented IgG4-related diagnosis. Check documentation if the record is unclear.
Coding tip
Confirm that the provider names IgG4-related disease explicitly; pathology language alone may not be enough without a supporting diagnosis statement.