A 6-year-old boy was admitted because of fever, purpura and upper abdominal tumors.
Hematological study revealed hemoglobin 10.2 g/dl, platelets 64,000/cmm, leukocytes 3,800/cmm with 12% blasts. Bone marrow smear showed 82.5% blasts which were large in size, abundant in basophilic cytoplasm and had a round nucleus with lacy chromatin and 2 or 3 nucleoli. The blast cells were negative for myeloperoxidase and weakly positive for PAS. About 85% blasts were positive for α-naphthyl butylate esterase staining which was inhibited in the presence of NaF. A diagnosis of acute monoblastic leukemia (FAB, M5a) was made.
The cytogenetic study of the blast cells showed an abnormal Karyotype of 47, XY, +8, ins (2; 11) (p25; q13q23).
Abdominal CT revealed large tumors occupying the whole abdominal cavity, which was interpreted as peritoneal involvement by the leukemic cells.
He was treated with ACMP 2-step therapy and a complete remission was obtained. However, relapse occurred after 2 months in the central nervous system and after 3 months in the bone marrow. Reinduction chemotherapy was done but no remission was achieved.
Chromosome 11q rearrangement with a breakpoint of q23 is possibly related to acute leukemia with monocytic differentiation.
Abnormal Karyotype of ins (2; 11) (q25; q13q23) has not been reported in acute monoblastic leukemia previously.