Double hit B-cell lymphomas with concurrent MYC and BCL2 rearrangements are well described and are associated with a rapidly progressive clinical course and dismal prognosis. Cases of double hit myeloma, however, are rare, and there are no reported cases of double hit plasma cell leukemia (PCL). Here, we describe the case of an aggressive plasma cell leukemia characterized by simultaneous IGH/MYC and IGH/BCL2 translocations. Two new cell lines have subsequently been derived from this case.
A 42-year old female was referred to hospital with a one-week history of blurred vision and bone pain on a background of three months of weight loss and lethargy. Physical examination was remarkable for a proptosed left eye and moderate hepatosplenomegaly.
Laboratory evaluation demonstrated moderate anemia (Hb 93 g/L), leukocytosis with plasmacytosis (WCC 23.10×10/L, circulating plasma cells 10.4×10/L, neutrophils 6.01×10/L) and moderate thrombocytopenia (platelets 68×10/L).
Serum protein electrophoresis revealed hypogammaglobulinemia. Serum kappa free light chains were elevated at 136.2 mg/L (normal range 3.3–19.4 mg/L), Lambda free light chain 1.0 mg/L (normal range 5.7–26.3 mg/L), ratio 136.20 (normal ratio 0.26–1.65). Monoclonal kappa free light chains were detected on urine protein electrophoresis. β2 microglobulin was 9.1 mg/L. Renal function and serum calcium were normal. Liver function testing demonstrated a predominantly cholestatic picture: GGT 556 U/L (normal <38), ALP 139 U/L (normal 36–106), ALT 76 U/L (normal 9–36). Bilirubin was normal. There was evidence of spontaneous biochemical tumor lysis: markedly elevated LDH 6540 U/L (normal range 125–255 U/L) with hyperuricemia (uric acid 0.61 mmol/L; normal range 0.11–0.36 mmol/L) and hyperphosphatemia (1.37mmol/L; normal range 0.6–1.3 mmol/L).
Computed tomography of the orbits revealed an 18×31×34 mm homogenously enhancing soft tissue mass in the superior left orbit.
Bone marrow biopsy demonstrated complete replacement of normal hematopoietic tissue with immature plasmablasts. Immunophenotypic analysis by flow cytometry utlizing the EuroFlow MM MRD panel1 confirmed clonal plasma cells (CD38, CD138, CD45, CD56, CD19, CD27, CD117, CD81 and Kappa). Immunohistochemical studies on trephine sections were positive for CD138, Ki67 (60%), c-MYC and BCL2.
Conventional cytogenetics (G-banding) was performed according to standard protocols and reported using the ISCN 2013 nomenclature.2 Multicolor FISH (M-FISH) and locus-specific probe FISH, using XCyte 24 probes (Metasystems), ON MYC/IGH t(8;14) dual fusion translocation probe (Kreatech) and LSI IGH/BCL2 t(14;18) dual color dual fusion translocation probe (Vysis) were performed according to the manufacturers’ instructions and revealed the following complex karyotype (Figure 1): 45,X,-X,der(1;8)(8pter->8q24::18q21->18q23::1p¿12->1qter), der(14)t(8;14)(q24;q32)x2,der(18)t(14;18)(q32;q21)[30]. ishder(1;8)(MYC+,IGH+;IGH+,BCL2+),der(14)t(8;14)(IG H+,MYC+), der(18)t(14;18)(BCL2+,IGH+)[30].
Overall, the findings were consistent with a diagnosis of primary plasma cell leukemia (pPCL). The patient was administered intravenous dexamethasone 40 mg and supportive therapy, which consisted of hydration and rasburicase and allopurinol. However, within 36 h of presentation, rapid clinical deterioration ensued. The patient developed multi-organ failure including acute liver failure causing lactic acidosis (pH 6.9). WCC increased to 123.4×10/L, circulating plasma cells 102.82×10/L, along with evidence of worsening tumor lysis. Despite maximal inotropic support and hemodiafiltration, acidemia continued to worsen and the patient died within 48 h of initial presentation.
Plasma cell leukemia is rare and the most aggressive variant of multiple myeloma (MM), representing 1%–2% of MM cases at diagnosis.3 PCL is defined as circulating peripheral blood plasma cells exceeding 2×10/L and plasma cells comprising 20% or more of peripheral blood white cells. Prognosis of primary PCL (pPCL) is poor with a median survival of 15 months for patients treated with novel agents.4 The molecular basis of PCL is less well understood than MM,5 with reported data based largely on retrospective studies. In contrast to MM, where 60% of cases are characterized by chromosomal gains, more than 80% of patients with PCL have hypodiploid or diploid cells.5 Chromosome 13 deletion and monosomy are frequent abnormalities. The frequencies of IgH (14q32) translocations by FISH are also high, reported in up to 87% of cases of pPCL, and in a Mayo Clinic study the frequency of t(11;14) in pPCL was 71%.6 In contrast to the relatively favorable prognosis conferred by the presence of t(11;14) in MM, the high prevalence in pPCL when coupled with high-risk cytogenetics, such as loss of p53, confers a poor prognosis (p53 loss due to mutation or deletion is observed in 56% of pPCL). Only 15% of pPCL have an MYC translocation; Tiedemann et al., found that MYC rearrangements predicted for shorter overall survival.6
Double hit B-cell neoplasms are defined by a chromosomal breakpoint affecting MYC/8q24 locus in combination with another recurrent breakpoint, generally a t(14;18)(q32;q21) involving BCL2 (other oncogenes implicated are BCL6 and CCND1). Double hit B-cell lymphomas are well characterized.7 However, cases of double hit MM are rare, with only 5 cases reported in the literature8 and none of double hit PCL.
In this present case of double hit pPCL, the sequence of events cannot be established with certainty but results suggested that the t(14;18) occurred prior to the t(8;14). After a reciprocal t(14;18), a second translocation involving 8q24 and IGH on the derivative 14, with the breakpoint proximal to the IGH-MYC fusion, resulted in the co-location of MYC, IGH and BCL2 signals on the der(8) and an IGH-MYC fusion on the der(14). There was a subsequent doubling of the der(14), loss of the normal 14 and an extra copy of 1q translocated onto the chromosome 18 sequences on the der(8). The net result was the t(14;18) and two copies of the der(14)t(8;14). The t(14;18) has only been reported in a handful of MM cases and only once with a simultaneous t(8;14).9
The rapid demise of this patient reflects the synergistic actions of the MYC and BCL2 oncogenes and is in contrast to 2 other reported cases of double hit MM: a case of IGH/MYC and IGH/BCL2 with plasmablastic morphology surviving eight months from diagnosis,9 and a case of IGH/MYC and IGH/CCND1 with plasmacytic morphology surviving 18 months from diagnosis.8
Two human myeloma cell lines have been propagated from the peripheral blood and bone marrow aspirate collected at time of presentation (ALF-1: derived from peripheral blood; ALF-2: derived from bone marrow). Karyotypic analyses utilizing M-FISH and G-banding show ALF-1 karyotype to be similar to ALF-2 but with additional numerical and structural changes (Figure 1), including a gain of 1q, all abnormalities acquired typically during disease evolution and a feature of progressive MM. In addition to karyotypic differences, these cell lines demonstrate further biological heterogeneity relating to the interaction between the MM cells and the bone marrow microenvironment.
Protein expression of CXCR4 by flow cytometry, a critical regulator of MM cell migration and homing to the bone marrow through interaction with its ligand SDF-1a,10 was reduced in ALF-1 compared with ALF-2 (Figure 2A.). Reduced CXCR4 expression has been shown to be associated with extramedullary disease in both a mouse model of MM11 and in primary patient samples,12 as well as predicting for inferior survival in MM patients treated with bortezomib.11 Interestingly, Singh et al.12 hypothesized that this was likely limited to a subpopulation of neoplastic cells, which is demonstrated in this case. CD45 expression by flow cytometry was higher in ALF-2 (CD45++, intermediate) compared to ALF-1 (CD45, dim) (Figure 2B.). Kumar et al.13 report that predominance of CD45- PCs in BM indicates a late stage of disease and portends a less favorable prognosis. In a murine myeloma model, 5T2MM, Asosingh et al.14 demonstrated that at pre-angiogenic phase, MM cells consisted mainly of CD45 cells. With disease progression, a process of ongoing differentiation of CD45 MM cells to CD45 MM cells occurs till the end of the pre-angiogenic stage at which most of the MM cells were CD45-. In this case study, the decline of CD45 and CXCR4 expression in the peripheral blood-derived cell line (ALF-1) compared to the bone marrow-derived cell line (ALF-2) suggests these switches are induced, and are in concert with solid tumorigenesis, indicating the occurrence of metastasis.
This unique case represents an extreme presentation of primary plasma cell leukemia, novel firstly in terms of the simultaneous double hit IGH/MYC and IGH/BCL2 translocations identified. Secondly, the biological heterogeneity of the two propagated cell lines recapitulate earlier published observations/hypotheses regarding medullary versus extramedullary disease, highlighting in particular the ‘metastatic’ phenotype of the circulating plasma cells.
References
- van Dongen JJ, Lhermitte L, Böttcher S. EuroFlow antibody panels for standardized n-dimensional flow cytometric immunophenotyping of normal, reactive and malignant leukocytes. Leukemia. 2012; 26(9):1908-1975. PubMedhttps://doi.org/10.1038/leu.2012.120Google Scholar
- Simons A, Shaffer LG, Hastings RJ. Cytogenetic nomenclature: Changes in the ISCN 2013 compared to the 2009 edition. Cytogenet Genome Res. 2013. Google Scholar
- Avet-Loiseau H, Roussel M, Campion L. Cytogenetic and therapeutic characterization of primary plasma cell leukemia: the IFM experience. Leukemia. 2012; 26(1):158-159. PubMedhttps://doi.org/10.1038/leu.2011.176Google Scholar
- van de Donk NW, Lokhorst HM, Anderson KC, Richardson PG. How I treat plasma cell leukemia. Blood. 2012; 120(12):2376-2389. PubMedhttps://doi.org/10.1182/blood-2012-05-408682Google Scholar
- Fernandez de Larrea C, Kyle RA, Durie BG. Plasma cell leukemia: consensus statement on diagnostic requirements, response criteria and treatment recommendations by the International Myeloma Working Group. Leukemia. 2013; 27(4):780-791. PubMedhttps://doi.org/10.1038/leu.2012.336Google Scholar
- Tiedemann RE, Gonzalez-Paz N, Kyle RA. Genetic aberrations and survival in plasma cell leukemia. Leukemia. 2008; 22(5):1044-1052. PubMedhttps://doi.org/10.1038/leu.2008.4Google Scholar
- Aukema SM, Siebert R, Schuuring E. Double-hit B-cell lymphomas. Blood. 2011; 117(8):2319-2331. PubMedhttps://doi.org/10.1182/blood-2010-09-297879Google Scholar
- Ji M, Jang S, Lee JH, Seo EJ. Double-hit myeloma with IGH/MYC and IGH/CCND1 translocations. Ann Hematol. 2013; 92(8):1129-1131. PubMedhttps://doi.org/10.1007/s00277-012-1668-yGoogle Scholar
- Kanungo A, Medeiros LJ, Abruzzo LV, Lin P. Lymphoid neoplasms associated with concurrent t(14;18) and 8q24/c-MYC translocation generally have a poor prognosis. Mod Pathol. 2006; 19(1):25-33. PubMedhttps://doi.org/10.1038/modpathol.3800500Google Scholar
- Alsayed Y, Ngo H, Runnels J. Mechanisms of regulation of CXCR4/SDF-1 (CXCL12)-dependent migration and homing in multiple myeloma. Blood. 2007; 109(7):2708-2717. PubMedhttps://doi.org/10.1182/blood-2006-07-035857Google Scholar
- Stessman HA, Mansoor A, Zhan F. Reduced CXCR4 expression is associated with extramedullary disease in a mouse model of myeloma and predicts poor survival in multiple myeloma patients treated with bortezomib. Leukemia. 2013; 27(10):2075-2077. PubMedhttps://doi.org/10.1038/leu.2013.148Google Scholar
- Singh Z, Owens RB, Nair B, Shaughnessy J, Barologie B. Loss of chemokine receptor expression and tetraspanins is correlated with extramedullary disease in multiple myeloma [abstract]. Blood (ASH Annual Meeting Abstracts). 2010; 116(21):2983. Google Scholar
- Kumar S, Rajkumar SV, Kimlinger T, Greipp PR, Witzig TE. CD45 expression by bone marrow plasma cells in multiple myeloma: clinical and biological correlations. Leukemia. 2005; 19(8):1466-1470. PubMedhttps://doi.org/10.1038/sj.leu.2403823Google Scholar
- Asosingh K, De Raeve H, Menu E. Angiogenic switch during 5T2MM murine myeloma tumorigenesis: role of CD45 heterogeneity. Blood. 2004; 103(8):3131-3137. PubMedhttps://doi.org/10.1182/blood-2003-08-2946Google Scholar