[Electron microscopic cytochemistry of pseudo-Chediak-Higashi granules in 5 cases of AML]

Blasts from 5 cases of AML with pseudo-Chediak-Higashi granules were examined ultrastructurally and histocytochemically using peroxidase, acid phosphatase, high iron diamine (HID) and periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) stainings. Pseudo-Chediak-Higashi granules, which appeared as vacuole-like inclusions by light microscopy, generally contained electron-lucent materials. All pseudo-Chediak-Higashi granules were, positive for peroxidase but some were negative for acid phosphatase. Pseudo-Chediak-Higashi granules were HID positive, indicating that they contained sulfated glycoconjugates. Glycogen-like particles were observed in the pseudo-Chediak-Higashi granules with the PA-TCH-SP method, as occasionally observed in granules in drug resistant ALL blasts. In conclusion, the contents of pseudo-Chediak-Higashi granules, which seems to be formed by fusion of small granules, differed from those of normal azurophillic granules.