Vacuolated Glycogen-laden Leukemic Cells in a Case of Crisis Type Chronic Adult T-cell Leukemia

We present a unique case of crisis type chronic adult T-cell leukemia (ATL), in which the majority of leukemic cells had abundant periodic acid-Schiff (PAS)-positive cytoplasmic inclusions. These inclusions were found to be composed of glycogen because the PAS-positivity completely disappeared after digestion with amylase or human saliva. Electron microscopy also revealed that the inclusions consisted of aggregated beta particles of glycogen. The mechanism of glycogen accumulation in leukemic cells remains unknown; however, the presence of such inclusions in leukemic cells may be helpful diagnostically in T-lymphocyte malignancies.