Myeloproliferative neoplasms (MPNs) are a group of hematologic disorders characterized by clonal proliferation of myeloid lineage cells. The diagnostic criteria are based on morphological features of bone marrow and peripheral blood cells but also include specific genomic mutations.

In some patients, co-occurrence of hematologic and rheumatic diseases could be observed. To date, most of the reported cases concerned patients with myelodysplastic syndrome (MDS) or essential thrombocythemia (ET).

In this paper, we present a case of a patient with a complicated diagnostic process leading to the diagnosis of unclassified MPN and giant cell arteritis (GCA). Routine tests did not reveal any mutations typical for MPNs such as JAK-2, CALR, MPL or BCR-ABL. Targeted next-generation sequencing (NGS) helped to confirm the diagnosis by demonstrating the presence of heterozygous ASXL1, TET2, SRSF2, and CBL mutations. The second important issue was the overlapping of symptoms of MPN and seronegative rheumatic disease, which finally was diagnosed as GCA. Leukocytosis and musculoskeletal pain, which were present at the time of diagnosis, resolved after allogeneic hematopoietic stem cell transplantation but recurred after a few months along with decreasing donor cell chimerism. Differentiation of the causes of recurrence of the symptoms was an important issue. This case shows the diagnostic challenge posed by co-incidence of MPN and rheumatic disease, especially its atypical variants.

中文翻译：

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同种异体造血干细胞移植治疗的患者中并发未分类的骨髓增生性肿瘤和巨细胞动脉炎：一例病例并文献复习

骨髓增生性肿瘤（MPN）是一组血液疾病，其特征是髓系谱系细胞的克隆增殖。诊断标准基于骨髓和外周血细胞的形态特征，但也包括特定的基因组突变。

在某些患者中，可以观察到血液和风湿性疾病并存。迄今为止，大多数报告的病例都与骨髓增生异常综合症（MDS）或原发性血小板增多症（ET）的患者有关。

在本文中，我们介绍了一例患者，诊断过程复杂，导致未分类的MPN和巨细胞动脉炎（GCA）的诊断。常规测试未发现MPN的任何典型突变，例如JAK-2，CALR，MPL或BCR-ABL。有针对性的下一代测序（NGS）通过证明杂合性ASXL1，TET2，SRSF2和CBL突变的存在，有助于诊断。第二个重要问题是MPN和血清阴性风湿性疾病的症状重叠，最终被诊断为GCA。诊断时出现的白细胞增多和肌肉骨骼疼痛在异基因造血干细胞移植后消失，但几个月后又复发，同时供体细胞嵌合体减少。症状复发原因的鉴别是一个重要的问题。该病例显示了MPN与风湿性疾病（尤其是其非典型变种）的并发构成的诊断挑战。