One-micron plastic sections of human peripheral blood and bone marrow specimens and peroxidase cytochemistry: use in the differential diagnosis of acute leukemias.

Peripheral blood or bone marrow samples from 142 patients with hematologic disorders were prepared for light microscopic study using 1-micron plastic sections. The same methodology provided excellent material for ultrastructural study of the same samples. Sixty-one of these cases were studied by electron microscopy and have been reported elsewhere. The techniques employed allowed the study of peripheral blood, a specimen generated by a relatively noninvasive procedure. The methods used provided light or electron microscopic identification of glycogen or peroxidase. These methods provided rapid results. Both light microscopic results and electron microscopic data were available within the same time frame as were routine paraffin sections. Preparation of plastic sections for light microscopy makes use of simple, well-known techniques and uses inexpensive manual microtomes. These methods are, therefore, accessible to any routine histopathology laboratory. The same material (blocks) can then be submitted to any diagnostic electron microscopic laboratory for further analysis if necessary. The extra resolution afforded by use of thin plastic sections for light microscopy allows easy identification of cell types. We have found these methods useful in the accurate classification of many acute leukemias and suggest that such improvement in diagnosis should be made available to physicians concerned with the diagnosis and care of patients with hematologic disorders.