Cytologic diagnosis of multiple myeloma and macroglobulinemia in effusions.

The presence of effusion in association with multiple myeloma or macroglobulinemia is an unusual finding which generally occurs late in the course of the disease. Occasionally, cytoligic detection is a diagnostic problem. In both conditions, the fluid is characrerized by a high specific gravity and high protein content. In myeloma, plasma cells at varying stages of differentiation are present, while in macroglobulinemia atypical lymphocytes and plasma cells resembling those found in the blood and bone marrow are seen. Generally, the diagnosis can be readily made on the basis of clinical features, characteristics of the fluid and cytologic findings. In difficult cases, additional procedures helpful in establishing a definite diagnosis include methyl green pyronine stain, fluid electrophoresis and electron microscopy.