Expansion of paroxysmal nocturnal hemoglobinuria clones in MPLW515L mutation harboring primary myelofibrosis
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LETTER TO THE EDITOR
Expansion of paroxysmal nocturnal hemoglobinuria clones in MPLW515L mutation harboring primary myelofibrosis Keita Kirito 1 Received: 2 May 2020 / Accepted: 13 May 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Dear Editor, Paroxysmal nocturnal hemoglobinuria (PNH) is a hemolytic disease caused by the expansion of hematopoietic cells with an acquired somatic mutation in the PIG-A gene. PNH clones are frequently found in some types of bone marrow failure syndromes, including aplastic anemia and myelodysplastic syndrome (MDS). On the other hand, PNH clone cells are rarely found in myeloproliferative neoplasms (MPNs) [1]. Here, we present, for the first time, a case of MPLW515L harboring primary myelofibrosis (PMF) with a PNH clone. A 49-year-old male was referred to our hospital for anemia and thrombocythemia. At that time, his complete blood cell counts noted white blood cell counts of 12.3 X109/L, Hb of 10.5 g/dL, and platelet number of 492 X109/L. A peripheral blood smear showed leukoerythroblastosis. Bone marrow biopsy revealed hypercellular bone marrow with excess megakaryocytes (Fig. 1a). Increases in reticulin and collagen fibers were found (Fig. 1 b and c). Elevated LDH was also observed (940 U/L). The chromosomal analysis was normal. A molecular study revealed the existence of an MPLW515L mutation. The patient also complained of darkened urine; therefore, we assessed the presence of PNH-type red blood cells according to the standard guideline [2]. As shown in Fig. 1d, 99% of the granulocytes had a fluorescein-labeled proaerolysin (FLAER) (−)/CD24(−) phenotype and 99 of monocytes were FLAER(−)/CD14(−). Based on these findings, we diagnosed the patient with PMF with the PNH clone. Although the incidence of this condition is low, the association between the PNH clone and MPN has been reported by
* Keita Kirito [email protected] 1
Department of Hematology and Oncology, University of Yamanashi, 1110, Shimokato, Chuo-city, Yamanashi-ken 409-3898, Japan
some groups [3–7]. Sugimori and colleagues reported three cases of PNH with the JAK2V617F mutation [4]. Langabeer et al. reported a patient with PNH-aplastic anemia with the JAK2V617F-positive clone [5]. The presence of PNH clones in CALR mutation-positive MPN patients has also been reported [6]. In addition, we reported a case of PMF with the MPLW515L mutation and the PNH clone. These findings indicated that the PNH clone could be present in any type of MPN, independent of the type of driver mutation. The clinical significance of the presence of PNH clones in MPN is not well established. One possible hypothesis is that the presence of PNH clone cells might increase the thromboembolic risk. Indeed, two of the three cases reported by Sugimori et al. were complicated with Budd Chiari syndrome [4]. Recently, to explore this hypothesis, Gutwein et al. analyzed the prevalence of PNH clones within 98 MPN patients [7]. They found that two patients (2%) had PNH clone cells and one patient actually showed recurrent complicati
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