Myeloid/Natural Killer Cell Precursor Acute Leukemia Accompanied by Homozygous Protein C Deficiency

A patient with myeloid/natural killer (NK) cell precursor acute leukemia who was also homozygous for protein C deficiency was treated and showed a complete remission while he simultaneously received low molecular weight heparin. He presented with fever spikes, lymphadenopathy, and a bulky tumor of the anterior mediastinum.A bone marrow aspirate showed the infiltration of immature lymphoblastoid cells. The patient’s diagnosis was determined to be myeloid/NK cell precursor acute leukemia by morphologic and immunophenotypic analysis (CD7+CD33+CD34+CD56+). The patient developed a thrombosis in his jugular vein on cannulation of the internal jugular vein. An examination of the serum levels and the activities of proteins C and S demonstrated a slight decrease in the protein C level but an undetectable protein C activity.The patient received the diagnosis of homozygous protein C deficiency, because both parents were found to have heterozygous protein C activity. Treatment of the patient’s leukemia included induction chemotherapy (Ara-C and idarubicin) with concomitant administration of low molecular weight heparin for his homozygous protein C deficiency. He achieved a complete remission without expressing any thrombosis during the course of chemotherapy.To our knowledge, this is the first case ever described in which acute myeloid leukemia was complicated with homozygous protein C deficiency. Int J Hematol. 2003;78:149-153.