Electron Microscopy as an aid to diagnosis in pediatric hematology/oncology

Abstract

This presentation is designed to demonstrate how scanning and transmission electron microscopy techniques can be utilized to confirm or support a variety of unusual pediatric hematologic/oncologic disorders. Patients with the following diagnoses will be presented: (1) hereditary pyropoikilocytosis, (2) familial erythrophagocytic lymphohistiocytosis, (3) acute megakaryoblastic leukemia, and (4) pseudo-von Willebrand’s disease.All transmission and scanning electron microscopy samples were fixed in 2.5% glutaraldehyde, rinsed in Millonig’s phosphate buffer, and post-fixed with 1% osmium tetroxide. The transmission samples were then en bloc stained with 0.5% uranyl acetate, rinsed with Walpole ’ s non-phosphate buffer, dehydrated with graded series of ethanols and embedded with Epon 812 epoxy resin. Ultramicrotomy thin sections were stained with uranyl acetate and lead citrate and scanned using a JEOL-JEM 100C, The scanning samples were dehydrated with graded series of ethanols, critical point dried with CO2, gold-coated, and scanned using a JEOL-JSM 35. The peroxidase samples were fixed in 3% glutaraldehyde, incubated in diaminobenzidine (DAB), dehydrated with ethanol, embedded with Epon 812, and scanned without post-staining using a JEOL-JEM 100C.