PMC6249888_01
Histopathological examination in hematoxylin-eosin. a: BM at the initial diagnosis of PMF, showing hypercellularity with some fat cells left (circle), clusters of mature granulocytes (closed arrow), singular and groups of atypical megakaryocytes (open arrow). b: BM at follow up, showing maximal cellularity without any fat cells left, no organized hematopoiesis with only singular mature granulocytes, a few atypical megakaryocytes, and clusters of immature cells and blast cells (asterisk). (Pictures: Friedemann Leh, Department of Pathology, Haukeland University Hospital)
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Fig1
There was reduced myelopoiesis, although without evidence of proliferation of immature cells (Fig. 1). BM biopsy demonstrated a hypercellular BM without organized hematopoiesis, absence of erythropoiesis and increased myelopoiesis with relatively few mature granulocytes, focal nodes of immature cells and blast cells and significantly increased amount of reticulin fibers (Fig. 1).
Chromosome analysis for detection of Philadelphia chromosome t(9; 22) in the patient. G-banding of diagnostic sample revealed a t(9;22)(q34;q11) (a) resulting in fusion of BCR and ABL verified by double fusion FISH from Vysis (b) and multiples RT-PCR (c). The multiplex (1 + 2) showed a 796 bp internal control (BCR) and 1051 bp BCR-ABL1 product generated by primer-combination BCR exon 1 and ABL1 exon 3 (2). The size gave suspicion of an e6a2 fusion verified by sanger sequencing using primer combination 2 (reverse sequence). (Picture: Randi Hovland, Haukeland University Hospital)
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Fig2
This was confirmed by BCR-ABL1 fusion in 57% of the cells by fluorescent in situ hybridization (FISH) analysis, (Fig. 2) and to be the BCR-ABL1 e6a2 transcript variant by sequencing of positive product from reverse transcriptase PCR.
Development of genetically, hematological and biochemical values during the follow up of the patient. The diagnosis of AML is set to time point 0, and the negative values indicate days before the AML diagnosis, and the positive value days after the AML diagnosis
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Fig3
Retrospectively, the e6a2 transcript was also detected at the initial diagnosis of PMF, although only with a BCR-ABL1/GUSB ratio of 14% (Fig. 3). BCR-ABL1/GUSB ratio fell from 52 to 7.6% after 3 months (Fig. 3). Because of increasing fatigability, the patient was referred to an echocardiography that showed a pericardial effusion of 1.8 cm at the level of the right atrium. Hgb 11.5 g/dL, WBC 5.3 x 109/L, neutrophils 2.8 x 109/L, and platelets 161 x 109/L. He continued imatinib therapy for 6 months and had detectable although stable levels of BCR-ABL1/GUSB ratio measured by qPCR during this period (Fig. 3).