A patient with basophilic-eosinophilic myeloproliferative disorder showing monosomy 7 and hyperhistaminemia.

We encountered a male patient with marked basophilia and eosinophilia complicated by anemia, thrombocytopenia, myelofibrosis, and hyperhistaminemia. Since morphological abnormalities were unclear and since chromosome analysis showed 45,XY,-7, a diagnosis of basophilic-eosinophilic myeloproliferative disorder was made. After administration of prednisolone and cytarabine ocfosfate, basophil and eosinophil levels decreased, but blasts transiently appeared in the peripheral blood. Chromosome analysis performed at the time of appearance of blasts showed a clone with 45,XY,-7,del(16)(q22). Subsequently, pancytopenia developed, after which white blood cell count and its classification were normal, as were chromosome findings. In this patient, monosomy 7 seemed to have induced myeloproliferative disorder with basophilia and eosinophilia, and del(16)(q22) may have enhanced the eosinophilia.