Identification of normal and abnormal human megakaryocytes based on acid fast metachromasia after staining with basic black MSP.

Megakaryocytes from normal persons and from patients with immune thrombocytopenic purpura, myelodysplastic disorders, hypersplenism, and essential thrombocythemia displayed vivid magenta metachromatic staining of the cytoplasm when stained with basic black MSP followed by brief exposure to dilute hydrochloric acid. Under the same conditions, other hematopoietic cells were completely decolorized. Acid fast metachromasia of megakaryocytes facilitates their identification, particularly in cases of small and atypical megakaryocytes found in disease states.