In multiple myeloma (MM), MYC rearrangements that result in increased MYC expression are associated with an aggressive form of MM and adverse outcome. However, the consequences of MYC amplification in MM remain unclear. Here, we describe an unusual case of plasma cell leukemia (PCL) harboring MYC amplification on double minute chromosomes (dmin). A 79-year-old woman was initially diagnosed as having BJP-κ type MM with bone lesions. After seven months, the disease progressed to secondary PCL: leukocytes 49.1 × 10⁹/L with 77% plasma cells showing lymphoplasmacytic appearance. The bone marrow was infiltrated with 76% plasma cells immunophenotypically positive for CD38 and negative for CD45, CD19, CD20, and CD56. The karyotype by G-banding and spectral karyotyping was 48,XX,der(14)t(11;14)(q13;q32),+der(14)t(14;19)(q32;q13.1),+18,6~95dmin[15]/46,XX[5]. Fluorescence in situ hybridization detected multiple MYC signals on dmin and double IGH/CCND1 fusion signals on der(14)t(11;14) and der(14)t(14;19). Most plasma cells were diffusely and strongly positive for MYC and CCND1 by immunohistochemistry. The patient died of progressive disease after one week. MYC amplification led to high expression of MYC and rapid disease progression, indicating its clinical significance in the pathogenesis of MM/PCL. MYC amplification on dmin may be a very rare genetic event closely associated with the progression to PCL and coexistence of IGH/CCND1 fusions.

在多发性骨髓瘤（MM）中，导致MYC表达增加的MYC重排与MM的侵袭性形式和不良预后相关。但是，MM中MYC扩增的后果仍不清楚。在这里，我们描述了一个罕见的浆细胞白血病（PCL）病例，它在双分钟染色体（dmin）上具有MYC扩增。最初诊断出一名79岁的妇女患有BJP-κ型MM并伴有骨病变。七个月后，疾病发展为继发性PCL：白细胞49.1×10 ⁹/ L与77％的浆细胞表现出淋巴胞浆的外观。骨髓浸润了76％的浆细胞，对CD38免疫表型呈阳性，而对CD45，CD19，CD20和CD56呈阴性。通过G带和光谱核型分析的核型为48，XX，der（14）t（11; 14）（q13; q32），+ der（14）t（14; 19）（q32; q13.1），+ 18,6〜95dmin [15] / 46，XX [5]。荧光原位杂交在dmin上检测到多个MYC信号，在der（14）t（11; 14）和der（14）t（14; 19）上检测到双IGH / CCND1融合信号。通过免疫组织化学，大多数浆细胞MYC和CCND1呈弥漫性和强阳性。该患者在一周后死于进行性疾病。我的C扩增导致MYC的高表达和疾病的快速发展，表明其在MM / PCL发病机理中的临床意义。dmin上的MYC扩增可能是非常罕见的遗传事件，与PCL的进展和IGH / CCND1融合的共存密切相关。