Intracellular immunoglobulin distribution of bone marrow plasma cells as a diagnostic aid for primary amyloidosis

In order to classify the underlying disorder in four patients with biopsy-proven amyloidosis without overt monoclonal gammopathy, the cytoplasmic immunoglobulin (Ig) distribution of bone marrow plasma cells was evaluated using direct immunofluorescence microscopy. This procedure revealed the presence of a monoclonal proliferation of light chain containing plasma cells, and thus led to the diagnosis of immunoglobulin-related amyloidosis.