False-Positive Galactomannan Test Results in Multiple Myeloma

Area of Science:

• Medical Mycology
• Hematology
• Infectious Diseases

Background:

• Invasive pulmonary aspergillosis (IA) is a significant complication in patients with hematological diseases.
• Early detection and treatment of IA are crucial for patient outcomes.
• The serum galactomannan antigen (GM) test is a widely used diagnostic tool for IA, adhering to EORTC/MSG criteria.

Purpose of the Study:

• To evaluate the diagnostic utility and potential for false positives of the serum galactomannan antigen (GM) test in patients with hematological diseases.
• To investigate the positivity rates of GM tests across different hematological malignancies and immunoglobulin types.
• To assess the implications of false-positive GM results in the context of IA diagnosis and management.

Main Methods:

• Retrospective analysis of serum galactomannan antigen (GM) tests performed between April 2003 and January 2012.
• Inclusion of 330 cases and 2155 samples in the analysis.
• Evaluation of GM test results against the 2008 EORTC/MSG criteria for IA diagnosis.

Main Results:

• Overall GM positivity rate was 25% (540/2155 samples).
• Multiple myeloma (MM) showed the highest positivity rate (61.3%), with IgG-type MM having a 71.7% positivity rate.
• Seventeen out of eighteen GM-positive MM cases were identified as false positives based on EORTC/MSG criteria.

Conclusions:

• Serum galactomannan antigen (GM) testing in patients with hematological diseases, particularly IgG-type multiple myeloma, is prone to false-positive results.
• These findings necessitate cautious interpretation of GM test results in specific patient populations.
• Further investigation into subclinical IA and the impact of anti-myeloma treatments on GM values is warranted.