Improved Outcome of Primary Plasma Cell Leukemia in the Current Era with the Use of Novel Agents and Autologous Bone Marrow Transplants-A Single Centre Experience.

Primary Plasma cell leukemia (pPCL) is an aggressive variant of plasma cell dyscrasias. Diagnostic criteria of plasma cell leukemia were recently updated by international myeloma working group to with more than 5% circulating plasma cells or absolute plasma cell count of more than 500/µL. We performed a retrospective analysis of patients diagnosed with pPCL in our department from 2017 to 2022. Clinical characteristics including the symptoms at presentation, organomegaly, bony involvement and extramedullary involvement were collected. Laboratory parameters including the biochemistry serum protein electrophoresis, serum immunofixation, serum free light chain assay, immunoglobulin profile were sent. Treatment and follow up data was collected. Fifteen patients were diagnosed (8 females and 7 males), median age 59 years (34-70). Six were lost to follow up and nine patients who received treatment at our hospital were analyzed for survival outcome. First line treatment was bortezomib- dexamethasone and immunomodulatory drugs (IMiD). Six (66%) achieved partial response or more and 3 had progressive disease. Five of the nine patients (55%) underwent autologous transplantation. Two out of 5 patients (40%) in the transplant group and 3 of the 4 patients (75%) in the non transplant group have died of the progressive disease. Overall survival was 45% at a median follow up of 14 months. Median OS for patients who underwent auto SCT was 16 months (12-22) versus 10 months (8-12) for patients who did not undergo transplant (Student t test; p value 0.018). Three of the patients achieved MRD negativity after transplant and post transplant consolidation therapy. Survival appears to be improved in patients who respond to initial therapy and are able to achieve MRD negativity which should be the goal of treatment in these patients.

Venetoclax in the treatment of secondary plasma cell leukemia with translocation t(11;14): a case report and literature review.

Introduction: Venetoclax is a BCL-2 inhibitor with proven efficacy in patients with multiple myeloma (MM) and translocation t(11;14). However, its role in plasma cell leukemia (PCL) remains unclear. Herein, we aimed to report a case of relapsed MM with secondary PCL and t(11;14) achieving complete (CR) and durable remission with venetoclax therapy. Case presentation: A 52-year-old gentleman was diagnosed with MM-free light chain lambda (ISS III) in December 2016. He received induction therapy, followed by autologous stem cell transplant. (ASCT) in May 2017 and maintenance. A year later, the patient relapsed with secondary PCL. His cytogenetics analysis revealed t(11; 14). The patient failed salvage chemotherapy and was shifted to venetoclax with dexamethasone treatment. The patient attained complete remission (CR), which was maintained for two years and a half before he developed fatal COVID-19 pneumonia. Conclusion: In comparison with the reported literature, this case report offers the latest compilation of the available evidence on the use of venetoclax in patients with PCL. Furthermore, our patient achieved CR for the longest reported durable response in literature thus far. Prospective clinical trials are needed to elucidate the optimal dosage, combination, and duration of treatment, ensuring better representation and generalizability of the findings. Meanwhile, venetoclax may be considered as a therapeutic option in patients with PCL t(11;14).

Development of a clinical prognostic model for primary plasma cell leukemia patients treated with novel agents: a multicenter retrospective cohort study.

The prognosis of primary plasma cell leukemia (pPCL) is poor, and the relevant prognostic factors are incompletely understood. We aimed to explore the prognostic factors and develop a validated prognostic prediction model for pPCL patients in the new era. This multicenter retrospective study was conducted across 16 hospitals in China. Cox proportional hazards regression analysis was used to develop a prediction model. The predictive performance of the model was assessed using multiple metrics. Internal validation was conducted using bootstrap resampling. A total of 102 pPCL patients were included in this study, and 57 (55.9%) were male. The 12-month, 24-month, and 36-month OS rates for pPCL patients were 75.4%, 58.3%, and 47.6%, respectively. An overall survival prognostic nomogram for pPCL patients was established by integrating independent prognostic factors, including age, B2MG, and del17p. The nomogram exhibited good performance, with a C-index of 0.720 (95% CI 0.642-0.797) and an AUC of 0.653. Bootstrap validation yielded a C-index of 0.721 (95% CI 0.629-0.787) and an AUC of 0.653 (95% CI 0.546-0.759), indicating a relatively good fit of the calibration curve. A nomogram incorporating age, B2MG grade, and del17p were developed and validated to accurately and consistently predict the prognosis of pPCL patients.

A Clinical Perspective on Plasma Cell Leukemia: A Single-Center Experience.

Circulating plasma cells (CPCs) are detected in most multiple myeloma (MM) patients, both at diagnosis and on relapse. A small subset, plasma cell leukemia (PCL), represents a different biology and has a poor prognosis. In this retrospective analysis, we evaluated patients with primary (pPCL, n = 35) or secondary (sPCL, n = 49), with ≥5% CPCs and a smaller subset with lower CPCs of 1-4% (n = 20). The median age was 61 years; 45% were men and 54% were Black. High-risk cytogenetics were found in 87% and extramedullary disease in 47%. For the entire cohort, 75% received a proteasome inhibitor, 70% chemotherapy, 54% an immunomodulatory drug, 24% a daratumumab-based regimen and 26% an autologous stem cell transplant (ASCT). The treatments marginally improved the overall survival (OS) for pPCL vs. sPCL (13 vs. 3.5 months p = 0.002). However, the 5-year survival for the whole cohort was dismal at 11%. High-risk cytogenetics, low platelets, extramedullary disease and high LDH were independently associated with poor outcomes. Further research is urgently needed to expand the treatment options and improve the outcomes in PCL.

Application and pitfalls of immunophenotyping in challenging plasma cell neoplasms: A case series.

Multiple myeloma (MM) is an incurable malignant plasma cell neoplasm, representing the second most common hematopoietic cancer. As plasma cell neoplasms are clonal and often secrete a monoclonal protein (M-spike), laboratory diagnosis is usually straightforward, especially when ancillary studies such as immunohistochemistry, flow cytometry, and protein electrophoresis are available in addition to microscopic examination. Despite the repertoire of diagnostic tools, rare cases pose diagnostic dilemmas, especially when reagent antibodies do not react as expected, extent of disease is patchy, or when disease occurs in unique age groups. In this retrospective study, we report a series of challenging diagnostic cases, discussing aberrant findings and comparing them to more classic counterparts. Twelve cases collected during routine clinical sign-out were reanalyzed and include examples of MGUS, classic multiple myeloma, t(11; 14) rearranged myeloma, minimal residual disease, AA and AL amyloidosis, truncated light chain, non-secretory and non-producer myeloma, biphenotypic myeloma, oligoclonal expansion after bone marrow transplant, and plasma cell leukemia in a young adult. This cohort showcases the diversity of atypical presentations of plasma cell neoplasms, and we highlight standardized approaches to workup to avoid diagnostic pitfalls.

Single-Center Experience of Patients with Plasma Cell Leukemia in the Era of New Therapeutics.

INTRODUCTION: Plasma cell leukemia (PCL) can occur de novo as primary PCL (pPCL), or in patients with prior diagnosis of multiple myeloma (MM) as secondary PCL (sPCL). In 2021, the diagnostic criteria have been revised, establishing a new cut-off of ≥5% plasma cells in the peripheral blood. Lacking specific clinical trials, PCL is treated similarly to MM; however, outcome for patients with PCL remains poor. Here, we report outcomes for patients with pPCL and sPCL in the era of novel agents. METHODS: We performed a retrospective analysis and identified 19 patients (11 pPCL, 8 sPCL) who have been treated for PCL between 2010 and 2022 at University Hospital Essen. RESULTS: Patients with pPCL had a median overall survival (OS) of 37.8 months (95% CI: [15.4; 52.3] months) from diagnosis, with a median time to next treatment (TTNT) of 18.4 (2.0; 22.9) months. All patients were treated with a proteasome-inhibitor (PI)-based induction therapy, and the majority was consolidated with an autologous stem cell transplantation (SCT). Five of these patients received a tandem transplantation. Patients with sPCL had a median OS of only 1.5 months after diagnosis of PCL. Only 1 patient achieved a remission with daratumumab and subsequent allogenic SCT. CONCLUSION: With our study, we add evidence for a PI-based induction therapy followed by a consolidating autologous SCT for patients with pPCL and give further evidence that a tandem transplant concept might be beneficial. The diagnosis of sPCL remains devastating and needs new therapeutic approaches.

Early Detection and Diagnostic Approach Through Automated Hematological Analysis for Plasma Cell Leukemia.

Plasma cell leukemia (PCL) is a clinically aggressive variant of multiple myeloma, characterized by a high burden of circulating plasma cells, necessitating swift and accurate diagnosis due to its poor prognosis. The conventional diagnostic criteria, including the recent recommendation by the International Myeloma Working Group (IMWG) of > 5% circulating plasma cells as positive, have evolved over time. In this context, we present a detailed case report that underscores the pivotal role of the ADVIA 2120 automated hematology counter in detecting plasma cells through cytogram analysis, along with the significance of routine peripheral blood smear analysis and the utility of a large unstained cells (LUCs) threshold of > 4.5% as an indicator for PCL. The case involves a 64-year-old patient with relapsed multiple myeloma and stable paraprotein levels who experienced sudden renal impairment. In this case report, we highlight how ADVIA analysis and cytochemistry assisted in the diagnosis, and further explore ADVIA's utility in this challenging leukemia.

Plasma Cell Leukemia-Clinicopathological Profile from a Tertiary Care Center in Western India.

Poornima ManimaranIntroduction Plasma cell leukemia (PCL) is very uncommon and aggressive neoplasm constituting 2 to 4% of all plasma cell dyscrasias. By definition, clonal plasma cells should make up 20% of peripheral blood or have an absolute plasma cell count of 2 × 10 9 cells/cu.mm. PCL can be primary or secondary. In this study, the clinicohematological features of PCL, and correlation of immunophenotypic profile and conventional therapies with overall survival was analyzed. Materials and Methods This retrospective study involved PCL patients who were diagnosed across a 12-year period, from 2010 to 2021, at a tertiary care center in western India. Clinical, biochemical, peripheral smear, bone marrow aspirate, immunophenotyping, and molecular analysis were performed. Results Total 39 PCL patients were included in the study among which 36 were primary PCL patients. Splenomegaly (10/27), hepatomegaly (6/26), and lymphadenopathy (5/23) were noted. At presentation, all patients had anemia (<11g/dL), thrombocytopenia (33/39), hypercalcemia (>11mg/dl) 10/33 (30.3%) and lytic lesions was noted in 18/26 (69.2%). Immunophenotype of these patients showed CD 38 positivity, CD 138 positivity, CD56 positivity, and CD 117 negativity were 100, 62, 41.6, and 89%, respectively. Overall survival of our patients was 4.1 months and overall survival of patients treated with VTD (bortezomib, thalidomide, dexamethasone) and VCD (bortezomib, cyclophosphamide, dexamethasone) regimen was 3.4 and 4.1 months, respectively, which was not statically significant ( p -value 0.816). CD117 and CD56 markers were also not having any prognostic significance ( p -value 1.000 and 0.873, respectively). Conclusion Because of rarity of the disease, prospective studies are very limited and hence management and outcome of the disease are difficult to analyze. The current treatment protocols have no survival advantage and hence newer therapeutic approach is mandatory to attain better outcome.

[Effect of Circulating Plasma Cells on the Prognosis of Patients with Multiple Myeloma].

OBJECTIVE: to analyze the effect of circulating plasma cells(CPC) on the prognosis of patients with multiple myeloma(MM) in the era of new drugs, and to explore the new definition standard of primary plasma cell leukemia(pPCL). METHODS: The clinical data of 321 patients with newly diagnosed MM and 21 patients with pPCL admitted to our hospital from January 2014 to May 2022 were retrospectively analyzed. According to the proportion of CPC in peripheral blood smears, all patients were divided into 4 groups: CPC 0% group(211 cases), CPC 1%-4% group(69 cases), CPC 5%-19% group(41 cases) and CPC≥20% group(21 cases). The clinical features of patients in each group were compared and the prognosis fators was analyzed. RESULTS: The median OS of the four groups were 44.5,21.3,24.6 and 12.8 months, respectively. Among them, 295 patients(86.3%) were treated with new drugs, and the median OS of the four groups were not reached, 26.7, 24.6 and 14.9 months, respectively. As the survival curves of CPC 5%-19% group and CPC≥20% group were similar, the patients were divided into CPC<5% group and CPC≥5% group, the median OS of CPC<5% group was better than that in CPC≥5% (43.5 vs 22.3 months, P<0.001). In addition, the median OS of patients in the CPC 1%-4% group was also significantly lower than that in the CPC 0% group and similar to that in the CPC≥5% group. Multivariate analysis showed that 1%-4% CPC was an independent risk factor for the OS of patients with CPC<5%. The patients with CPC<5% were stratified by R-ISS staging, and the OS of R-ISS stage Ⅰ or stage Ⅱ with 1%-4% CPC was similar to that of R-ISS stage Ⅲ. The newly defined pPCL patients showed increased tumor load and obvious invasive characteristics. Multivariate analysis showed no independent prognostic factors for pPCL, and high-risk cytogenetic abnormalities(HRCA) had no significant effect on the prognosis. CONCLUSION: The validity of IMWG's new pPCL definition standard was verified, and it was found that the survival of MM with 1%-4% CPC also is poor and the prognosis is very close to pPCL. In addition, the newly defined pPCL has unique clinical and biological characteristics.

Allogeneic Stem Cell Transplantation in Multiple Myeloma: Risk Factors and Outcomes in the Era of New Therapeutic Options-A Single-Center Experience.

BACKGROUND: Despite major treatment advances, multiple myeloma remains incurable. The outcome of patients who are refractory to immunomodulatory agents, proteasome inhibitors, and anti-CD38 monoclonal antibodies is poor, and improved treatment strategies for this difficult-to-treat patient population are an unmet medical need. METHODS: This retrospective, unicentric analysis included 38 patients with relapsed/refractory multiple myeloma or plasma cell leukemia who underwent allogeneic stem cell transplantation (allo-HSCT) between 2013 and 2022. Survival outcomes, relapse incidence, and non-relapse mortality were calculated according to remission status, date of allo-HSCT, cytogenetic risk status, timing, and number of previous autologous HSCTs. RESULTS: The median PFS was 13.6 months (95% CI, 7.7-30.4) and the median OS was 51.4 months (95% CI, 23.5-NA) in the overall cohort. The cumulative incidence of relapse at 3 years was 57%, and non-relapse mortality was 16%. The median PFS and OS were significantly longer in patients with very good partial remission (VGPR) or better compared to patients with less than VGPR at the time of allo-HSCT (mPFS 29.7 months (95% CI, 13.7-NA) vs. 6.5 months (95% CI, 2.6-17.0); p = 0.009 and mOS not reached vs. 18.6 months (95% CI, 7.0-NA); p = 0.006). CONCLUSION: For selected patients, allo-HSCT may result in favorable overall survival, in part by providing an appropriate hemato-immunological basis for subsequent therapies.

Improved Screening of Monoclonal Gammopathy Patients by MALDI-TOF Mass Spectrometry.

Monoclonal gammopathies are a group of blood diseases characterized by presence of abnormal immunoglobulins in peripheral blood and/or urine of patients. Multiple myeloma and plasma cell leukemia are monoclonal gammopathies with unclear etiology, caused by malignant transformation of bone marrow plasma cells. Mass spectrometry with matrix-assisted laser desorption/ionization and time-of-flight detection is commonly used for investigation of the peptidome and small proteome of blood plasma with high accuracy, robustness, and cost-effectivity. In addition, mass spectrometry coupled with advanced statistics can be used for molecular profiling, classification, and diagnosis of liquid biopsies and tissue specimens in various malignancies. Despite the fact there have been fully optimized protocols for mass spectrometry of normal blood plasma available for decades, in monoclonal gammopathy patients, the massive alterations of biophysical and biochemical parameters of peripheral blood plasma often limit the mass spectrometry measurements. In this paper, we present a new two-step extraction protocol and demonstrated the enhanced resolution and intensity (>50×) of mass spectra obtained from extracts of peripheral blood plasma from monoclonal gammopathy patients. When coupled with advanced statistics and machine learning, the mass spectra profiles enabled the direct identification, classification, and discrimination of multiple myeloma and plasma cell leukemia patients with high accuracy and precision. A model based on PLS-DA achieved the best performance with 71.5% accuracy (95% confidence interval, CI = 57.1-83.3%) when the 10× repeated 5-fold CV was performed. In summary, the two-step extraction protocol improved the analysis of monoclonal gammopathy peripheral blood plasma samples by mass spectrometry and provided a tool for addressing the complex molecular etiology of monoclonal gammopathies.

Racial Disparities in Plasma Cell Leukemia Outcomes Among Hospitalized Patients in the United States.

Plasma cell leukemia (PCL) is a rare, aggressive subtype of multiple myeloma (MM) with a poor prognosis. Prior studies have shown that racial disparities affect MM patients in various ways, which may affect patients' outcomes. In this study, we aimed to investigate racial differences in hospitalization outcomes for PCL using Nationwide Inpatient Sample data. Overall, hospitalization rates for PCL tended to decrease over the past decade. Among hospitalized patients with a primary diagnosis of PCL, there was no statistically significant association between race/ethnicity and hospitalization rates, between NH-White patients and NH-Black patients (OR 1.94; 95%CI 0.3-3.54, p 0.95), and Hispanic patients (OR 0.47; 95% CI 0.05-4.23, p 0.5). Additionally, there was no significant association between race/ethnicity and inpatient mortality. The overall lower incidence of PCL, more significant disease burden, and poor prognosis across all groups may contribute to our findings. With increasing evidence that PCL is cytogenetically distinct from MM, more investigation into biological and sociodemographic factors that affect healthcare utilization and treatment outcomes should be carried out.

Clinical and cytogenetic characteristics of primary and secondary plasma cell leukemia under the new IMWG definition criteria: a retrospective study.

BACKGROUND: Plasma cell leukemia (PCL) is a rare and aggressive plasma cell disorder, exhibiting a more unfavorable prognosis than multiple myeloma. PCL is classified into pPCL and sPCL. Recently, the IMWG has recommended new PCL definition criteria, which require the presence of ≥5% circulating plasma cells in peripheral blood smears. Due to its low incidence, research on pPCL and sPCL is limited. METHODS: We conducted a retrospective study and analyzed clinical and cytogenetic data of pPCL and sPCL patients. Overall survival (OS) and progression-free survival (PFS) were assessed by the Kaplan-Meier method, and survival distributions were compared using the log-rank test. RESULTS: This is a small cohort comprising 23 pPCL and 9 sPCL patients. Notably, sPCL patients showed a higher incidence of extramedullary infiltration and a higher percentage of bone marrow plasma cells (p = 0.015 and 0.025, respectively). Although no significant difference was found between the two groups in OS and PFS, a trend emerged suggesting a superior survival outcome for pPCL patients, with a higher cumulative 1-year PFS rate (38.3% vs. 13.3%) and a lower early mortality rate (mortality rate at 3 months: 15% vs. 33%). We also suggested that pPCL patients carrying t(11;14) may have a longer median survival time than individuals with other cytogenetic abnormalities, but this was not confirmed due to the small sample size. CONCLUSION: Our study revealed clinical and cytogenetic features of pPCL and sPCL patients according to the new diagnostic criteria. The findings suggested a generally better prognosis for pPCL than sPCL and the likelihood of t(11;14) translocation acting as a favorable prognostic factor in pPCL. It is important to note that our study had a limited sample size, which may lead to bias. We hope well-designed studies can be conducted to provide more results.

Kidney Biopsy Un-masquerading Plasma Cell Leukemia Diagnosed as Acute Myeloid Leukemia: An Unusual Clinical Experience.

Plasma cell leukemia (PCL) is a rare aggressive variant of plasma cell myeloma. The differential diagnosis of PCL includes multiple myeloma (MM), other leukemias, and lymphomas with abnormal cells circulating in the peripheral blood. In addition, infectious or autoimmune diseases can cause reactive polyclonal plasmacytosis, which could confuse us with PCL occasionally. Sometimes, blastoid morphology can cause confusion in diagnosis, and immunohistochemistry is needed to differentiate PCL from other forms of leukemias and lymphomas. Here, we present a rare case of PCL diagnosed as acute myeloid leukemia (AML) with kidney biopsy establishing the correct diagnosis.

Sequential autologous and allogeneic stem cell transplantation for treatment of primary plasma cell leukemia: A case report.

Primary plasma cell leukemia (pPCL) is a rare and aggressive form of plasma cell disorder, which accounts for ~70% of all PCL. Survival of pPCL remains poor, and is related with early mortality. There is no standard therapy for patients with pPCL. In the present study, a 26-year-old man who was diagnosed with pPCL was reported. The patient achieved stringent complete remission to the successful treatment of intensive chemotherapy combined with sequential autologous and allogeneic stem cell transplantation (SCT) followed by maintenance therapy with oral administration of ixazomib, thalidomide and dexamethasone (IRD regimen). Development of complex treatment algorithms that combine novel agents, SCT and post-transplantation remission strategies may translate into survival in patients with pPCL.

BCLXL PROTAC degrader DT2216 targets secondary plasma cell leukemia addicted to BCLXL for survival.

Secondary plasma cell leukemia (sPCL) is a rare form of aggressive plasma cell malignancy arising mostly at end-stage refractory multiple myeloma and consequently presenting limited therapeutic options. We analyzed 13 sPCL for their sensitivity to BH3 mimetics targeting either BCL2 (venetoclax) or BCLXL (A1155463) and showed that 3 sPCL were efficiently killed by venetoclax and 3 sPCL by A1155463. Accordingly, BH3 profiling of 2 sPCL sensitive to BCLXL inhibition confirmed their high BCLXL primed profile. While targeting BCLXL using BH3 mimetics induces platelets on-target drug toxicity, the recent development of DT2216, a clinical-stage BCLXL proteolysis targeting chimera PROTAC compound, provides an alternative strategy to target BCLXL. Indeed, DT2216 specifically degrades BCLXL via VHL E3 ligase, without inducing thrombocytopenia. We demonstrated in human myeloma cell lines and sPCL that sensitivity to DT2216 strongly correlated with the sensitivity to A1155463. Interestingly, we showed that low doses of DT2216 (nM range) were sufficient to specifically degrade BCLXL after 48 hours of treatment, consistent with VHL expression, in all cell lines but irrespectively to DT2216 sensitivity. In myeloma cells, DT2216 induced apoptotic cell death and triggered BAX and BAK activation. In conclusion, our study demonstrated that patients with sPCL addicted to BCLXL, a small but a very challenging group, could potentially receive therapeutic benefit from DT2216. Clinical trials of DT2216 in this subset of sPCL patients are warranted.

Efficacy and Safety Analysis of VRD-PDCE in Treatment-Native Patients with Multiple Extramedullary Plasmacytomas or Plasma Cell Leukemia.

The prognosis of multiple extramedullary plasmacytomas (MEP) and plasma cell leukemia (PCL) is extremely poor, with the median overall survival (OS) of only 8 months with standard chemotherapy. Innovative treatment approaches incorporating various strategies are required to improve outcome. From November 2019 to September 2021, a total of 12 newly diagnosed MEP or PCL patients were enrolled in our department. An intensive chemotherapy treatment as VRD-PDCE consisted of bortezomib, lenalidomide, dexamethasone plus cisplatin, pegylated liposomal doxorubicin, cyclophosphamide and etoposide was first proposed. Disease activity and toxicity were evaluated after each cycle. Of the patients receiving therapy achieved a rapid and sustained response, and the overall response rate (ORR) was up to 75%. Nine patients achieved partial response (PR) or better, the response was the best response and the median time to best response was 4 cycles. Median overall survival (OS) and progression-free survival (PFS) were 24 (5-30) months and 18 (2-23) months. The toxicities were acceptable and there was no treatment related mortality. Our intensive treatment showed encouraging results in terms of disease control and improving survival, VRD-PDCE may be a novel regimen which is feasible and generally well-tolerated in MEP or PCL patients.

[Clinical Characteristics and Survival Analysis of Patients with Plasma Cell Leukemia].

OBJECTIVE: To investigate the clinical characteristics, therapeutic response and prognosis of patients with plasma cell leukemia (PCL) and improve the understanding of this disease. METHODS: The clinical manifestations, laboratory tests and treatment response of 27 patients with plasma cell leukemia treated in The Second Hospital of Shanxi Medical University from December 2010 to August 2019 were analyzed retrospectively, and their clinical characteristics were summarized. Kaplan-Meier method was used for survival analysis. RESULTS: There were 18 cases of primary plasma cell leukemia (pPCL) and 9 cases of secondary plasma cell leukemia (sPCL). The male to female ratio was 1.7∶1. The median age was 62 years old. The first manifestations were bone pain, fatigue, fever, splenomegaly and bleeding, and a large number of plasma cell infiltration was observed in the morphological examination of peripheral blood and bone marrow cells. 13 cases were detected by immunotyping and all of them expressed CD38/CD138. 8 cases underwent karyotype analysis, and 3 cases were normal, clonal abnormalities occurred in 5 cases. FISH detection was performed in 12 cases, of which 8 cases were abnormal. In 17 cases of bortezomib based chemotherapy, the ovevall response rate was 52.9%, which was higher than that in the non-bortezomib group, but there was no significant difference between the two groups (P =0.242). The overall median survival time of 27 patients was 6.4 months, the median progression-free survival time was 3.5 months, and the median survival time of patients with pPCL and sPCL was 8.2 months and 2.4 months, respectively, the difference between the two groups was statistically significant (P =0.031). CONCLUSION: PCL is highly invasive and has diverse clinical manifestations, and is not sensitive to traditional chemotherapy. The median survival time of patients with pPCL is relatively longer than that of patients with sPCL. The chemotherapy regimen based on bortezomib improves the treatment effectiveness and prolongs the survival time of PCL patients.

Coincidence of plasma cell leukemia and COVID-19: a diagnostic pitfall.

We report the case of a 66-year-old man with a known history of IgD multiple myeloma (MM) which was admitted to hospital because of acute renal failure. Routine PCR testing on admission yielded a positive result for SARS-CoV-2 infection. Examination of the peripheral blood (PB) smear revealed 17% lymphoplasmacytoid cells and a few small plasma cells mimicking morphological changes frequently seen in viral diseases. However, flow cytometric examination showed 20% clonal lambda-restricted plasma cells being consistent with a diagnosis of secondary plasma cell leukemia. Circulating plasma cells as well as similar appearing lymphocyte subtypes such as plasmacytoid lymphocytes are frequently observed in infectious disorders such as COVID-19, so that the lymphocyte morphology in our patient's case could have been easily misinterpreted as typical COVID-19-induced changes. Our observation highlights the importance of incorporating clinical, morphological, and flow-cytometric data in distinguishing between reactive and neoplastic lymphocyte changes because misinterpretation may affect disease classification and, beyond that, clinical decision-making, which may have serious consequences for patients.