IgG4-related disease: what a hematologist needs to know

Area of Science:

• Immunology
• Pathology
• Hematology

Background:

• Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibro-inflammatory condition with diverse organ involvement.
• Hematologic manifestations, including lymphadenopathy and eosinophilia, are key features of IgG4-RD.
• IgG4-RD can be mistaken for other hematologic malignancies and disorders, complicating diagnosis.

Observation:

• Patients may present with symptoms mimicking multicentric Castleman disease, lymphoma, or hypereosinophilic syndromes.
• Serum protein electrophoresis and IgG subclasses aid initial suspicion, but histological confirmation is essential.
• Key histopathological findings include IgG4-positive plasma cells, storiform fibrosis, and obliterative phlebitis.

Findings:

• The review highlights hematologic manifestations such as lymphadenopathy, eosinophilia, and polyclonal hypergammaglobulinemia in IgG4-RD.
• Optimal sites for histological diagnosis exclude bone marrow and lymph nodes due to the absence of specific fibrotic features.
• While many patients respond to treatment, some experience severe complications, and durable remissions can be challenging.

Implications:

• Accurate diagnosis of IgG4-RD is critical to differentiate it from hematologic malignancies.
• Corticosteroids are effective but associated with significant side effects like new-onset diabetes.
• Further research into targeted therapies and biomarkers is needed for improved management of refractory IgG4-RD.