Benign and malignant (B cell) focal lymphoid aggregates in bone marrow trephines shown by means of an immunogold-silver technique.

A series of 36 iliac crest trephines, previously shown to contain follicular lymphoid aggregates, were examined using the immunogold-silver staining technique. This showed the presence of kappa and lambda surface immunoglobulin in paraffin sections of the specimens. In those trephines from patients known to be suffering from chronic lymphocytic leukaemia there was distinct monoclonality for expression of either kappa or lambda surface light chains on the lymphocyte cell surfaces in and usually between the lymphoid nodules. In specimens containing aggregates, which had previously been diagnosed as benign on morphological and clinical criteria, both kappa and lambda chains were expressed. A small number of trephines containing aggregates of uncertain nature were also examined; these all showed monoclonal expression of either kappa or lambda chains and subsequently proved to be clinically malignant. Dendritic reticulum cells, shown by staining for surface immunoglobulin, were observed only in benign aggregates.