Null cell (non-T, non-B) acute lymphoblastic leukemia terminating as malignant histiocytosis.

A case of null cell acute lymphoblastic leukemia (ALL) terminating in malignant histiocytosis (HMR) is discussed. The patient was a 22-year-old man who presented in January 1976 with ALL. Cell surface markers on the bone-marrow blasts showed that 1% formed rosettes with sheep erythrocytes (T cells) and 4% showed immunofluorescent staining for immunoglobulin; terminal transferase levels were elevated, confirming the diagnosis of null cell ALL.

Plasma cells with inclusions containing iron.

Iron inclusions in plasma cells of the bone marrow of an individual suffering from megaloblastic anemia due to folate deficiency were examined by electron microscopy. It seems that the iron is introduced into the plasma cell by micropinocytosis. The speculation of possible transfer of iron from the reticulum macrophage to the plasma cell is raised.