LAUSR

A nine-year-old girl presented with a 10-day history of pain in the left shoulder and abdomen, and was found to have superficial lymphadenopathy without any obvious cause. A full blood count showed a total leucocyte count of 18.75 9 10/l, a haemoglobin concentration of 79 g/l and a platelet count of 150 9 10/l. A peripheral blood film showed 70% abnormal cells with fine dust-like cytoplasmic granules and prominent nucleoli. Bone marrow (BM) aspirate films showed 90% abnormal cells with fine dust-like granules and regular round or oval nuclei with dispersed chromatin and prominent nucleoli (top, 9100 objective; Wright–Giemsa stain). In addition, peculiar rectangular crystal-like inclusions were seen in 1% of the abnormal cells. Myeloperoxidase (MPO) was strongly positive in almost all the leukaemic cells, but the rectangular crystals were MPO-negative (bottom, 9100 objective). Immunophenotyping of BM showed 89.6% abnormal cells, which were positive for CD33, CD13, CD9, CD123, CD64, CD117 (partial) and CD56 (partial), and were negative for CD34, HLA-DR, CD14, CD19, CD7, CD2, CD5 and CD20. Cytogenetic analysis showed 46,XX,t(15;17)(q24; q21)[6]. A PML-RARA fusion gene was detected by real-time quantitative PCR and fluorescence in situ hybridisation (FISH). A diagnosis of acute promyelocytic leukaemia was made. Acute promyelocytic leukaemia shows a wide spectrum of morphological abnormalities — in particular, large dense cytoplasmic granules, multiple Auer rods and kidney-shaped or bilobed nuclei. The presence of MPO-negative rectangular inclusions is very rare. Xiaohuan Mo and Hongwei Chen Department of Paediatrics, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China and Department of Clinical Laboratory, The First Hospital of Qinhuangdao, Qinhuangdao, China. E-mail: [email protected]