Prozone effect of serum IgE levels in a case of plasma cell leukemia

Area of Science:

• Hematology
• Clinical Chemistry
• Immunology

Background:

• Multiple myeloma (MM) is a plasma cell malignancy.
• Secondary plasma cell leukemia (PCL) is a rare, aggressive complication of MM.
• IgE-producing plasma cell neoplasms are exceptionally rare.

Observation:

• A unique case of MM with secondary PCL secreting IgE-kappa immunoglobulin is presented.
• Standard tumor markers like serum free light chains and Bence-Jones proteinuria were uninformative.
• Quantitative serum IgE levels yielded inaccurate results due to the prozone effect.

Findings:

• The prozone effect, caused by antigen excess, interfered with IgE detection methods.
• The M component measured by serum protein electrophoresis (SPEP) was the sole reliable marker for therapeutic response.
• Accurate interpretation of tumor markers is crucial for managing rare IgE-producing PCL.

Implications:

• Clinicians must be aware of the prozone effect and its potential to mask disease progression.
• Alternative or modified laboratory methods may be needed for accurate monitoring of IgE-secreting neoplasms.
• This case underscores the heterogeneity of plasma cell disorders and challenges in their laboratory assessment.