Acute nonlymphocytic leukemia (M7 subtype) with erythrocytic internalization.
A case of acute nonlymphocytic leukemia of megakaryocytic lineage or M7 with a conspicuous phenomenon of erythrocytic internalization present in nearly 3% of the leukemic megakaryocytic precursors (LMP) is reported. The phagocytosis was detected at light microscopy and ultrastructural levels. The erythrocyte might have reached the interior of the LMP through cytoplasmic vacuoles that are connected with the extracellular space and that can be considered rudimentary equivalents of the demarcation membrane system (DMS). Erythrocytic internalization is not a specific feature of the mononuclear phagocytic system and can be misleading in the classification of undifferentiated blast cells.
D001853:Bone Marrow / Q000473:pathology; D002675:Child, Preschool; D006801:Humans; D007938:Leukemia / Q000473:pathology*; D008297:Male; D008533:Megakaryocytes / Q000648:ultrastructure; D010587:Phagocytosis; D013920:Thrombocythemia, Essential / Q000473:pathology