Indian Journal of Pathology and Microbiology

CASE REPORT
Year
: 2020  |  Volume : 63  |  Issue : 3  |  Page : 485--487

Rare case of plasma cell myeloma with megakaryoblastic morphology mimicking acute leukemia


Keyu Liu1, Huijuan Song2, Jie Shi3, Weijun Zhang2, Rui Mu2, Li Li4,  
1 Department of Clinical Laboratory, Affiliated Hospital of Engineering University of Hebei, Hebei Province, China
2 Department of Clinical Laboratory, Affiliated Zhongshan Hospital of Dalian University, Liaoning Province, China
3 Department of Hematology, Affiliated Zhongshan Hospital of Dalian University, Liaoning Province, China
4 Department of Hematology, Affiliated Hospital of Engineering University of Hebei, Hebei Province, China

Correspondence Address:
Li Li
Department of Hematology, Affiliated Hospital of Engineering University of Hebei, Congtai Street Number 81, HanDan, Hebei Province
China

Abstract

Myeloma plasma cells vary from mature forms to immature, plasmablastic, and pleomorphic cells. Only a few cases of morphologic variant of plasma cell neoplasm have been reported, in which the plasma cell neoplasm presented with lymphoplasmacytic, megakaryocytic, plasmablastic, lymphocytosis-like, and variant hairy cell leukemia-like morphological features. A 66-year-old man sought medical attention with a previous 2-month history of lower back and chest pain. Magnetic resonance imaging (MRI) of the thoracic spine showed thoracic vertebral body shape and disc degeneration, and bone lesion. Blood work showed mild anemia (hemoglobin, 101 g/L; white blood cells, 6.98 × 109/L; platelets, 146 × 109/L.), hyperuricemia (UA 671 umol/L), and immunoglobulin G kappa [IgG(κ)] paraproteins. Bone marrow study revealed diffuse invasion by sheets of megakaryoblast-like cells. Flow cytometric analysis and bone marrow biopsy revealed plasma cell myeloma (PCM), and thoracic puncture biopsy indicated plasma cell neoplasms. Overall, the findings were in accordance with a PCM. To date, this is the first reported case of PCM with megakaryoblastic morphology mimicking acute leukemia. Recognizing the morphological variant of PCM is important in differentiating it from acute leukemia.



How to cite this article:
Liu K, Song H, Shi J, Zhang W, Mu R, Li L. Rare case of plasma cell myeloma with megakaryoblastic morphology mimicking acute leukemia.Indian J Pathol Microbiol 2020;63:485-487


How to cite this URL:
Liu K, Song H, Shi J, Zhang W, Mu R, Li L. Rare case of plasma cell myeloma with megakaryoblastic morphology mimicking acute leukemia. Indian J Pathol Microbiol [serial online] 2020 [cited 2020 Oct 29 ];63:485-487
Available from: https://www.ijpmonline.org/text.asp?2020/63/3/485/291664


Full Text



 Introduction



Usually connected with an M protein in urine or/and serum, PCM is a bone marrow-based multifocal neoplastic multiplication of plasma cells and shows evidence of organ damage associated with the plasma cell neoplasm generally. For nearly all PCMs, original site is bone marrow and diffuse infiltration of the bone marrow can be detected in most cases. Other organs may be frequently involved.[1] BM aspirate shows the proportion of myeloma plasma cells varies from barely a few to >90%. Mature forms, immature, plasmablastic, and pleomorphic myeloma plasma cells can be seen in PCM. Approximately 10% of the cases present with plasmablastic morphological features. In some cases, pleomorphic, multinucleated, multilobed plasma cells are prominent.

Several cases of morphological variant of plasma cell neoplasm have been reported so far, in which they presented with lymphoplasmacytic, megakaryocytic, plasmablastic, lymphocytosis-like, or variant hairy cell leukemia-like morphological features [Table 1].[2],[3],[4],[5],[6] We herein report the first case of PCM with megakaryoblastic morphology mimicking acute leukemia, which shows recognizing the morphological variant of PCM is significant in differentiating it from acute leukemia.{Table 1}

 Case Report



A 66-year-old man presented with a previous 2-month history of lower back and chest pain. Laboratory findings were as follows: White blood cell count was 6.98 × 109/L, hemoglobin was 101 g/L, platelet count was 146 × 109/L, total serum protein was 100.3 g/L, albumin was 45.3 g/L, lactate dehydrogenase (LDH) was 511 U/L, urea nitrogen was 5.41 mmol/L, creatinine was 120 umol/L, uric acid was 671 umol/L, serum calcium was 2.76 mmol/L, and human immunodeficiency virus was negative. MRI of the thoracic spine showed thoracic vertebral body shape and disc degeneration, and bone lesion. BM smears revealed diffuse infiltration of medium-sized blast-like cells (37.5%), which showed basophilic cytoplasm and cytoplasmic pseudopod formation, high nuclear-cytoplasmic ratio, fine chromatin and inconspicuous nucleoli [Figure 1]a and [Figure 1]b. The blasts were negative for myeloperoxidase and positive for periodic acid Schiff reagent [Figure 1]c and [Figure 1]d. The blasts were supported with megakaryoblast-like morphological and primary cytochemical staining features. Flow cytometry immunophenotyping revealed the abnormal plasma cell population with 13.66% of nucleated cells. The abnormal plasma cell population was positive for CD28, CD38, CD138, and CD200, weakly positive for CD56, CD81, and cKappa, and negative for CD27, CD117, CD19, CD20, CD41, CD61, and cLambda. The results of the immunophenotypic analysis suggested plasma cell neoplasm. Immunohistochemistry on bone marrow biopsy revealed that abnormal cells were positive for CD38, CD138, and Kappa, and negative for CD56, CD20, and Lambda. Bone marrow biopsy indicated PCM. Thoracic puncture biopsy indicated diffuse proliferation of medium-sized cells with rather large nucleus and heterotypical change in cell shape, and immunohistochemical stain revealed that the cells were positive for κ, bcl-2, CD138, Mum-1, and Ki67 (30%), and negative for CD3, CK, CD20, S-100, desmin, CD34, CD99, CD56, Syn, CD79, Pax-5, and Cyclin-D1. The histopathological findings of biopsy specimens of the thoracic puncture indicated plasma cell neoplasm. The M protein was identified by immunofixation electrophoresis (IFE) as immunoglobulin G kappa [IgG(κ)] [Figure 2]. Cytogenetic analysis of the BM cells revealed a 46, XY (20) karyotype. D13S319/RB1 probes were detected by using fluorescence in situ hybridization (FISH) technology.{Figure 1}{Figure 2}

 Result



To the best of our knowledge, PCM with blast-like morphology mimicking acute leukemia is rare. Given that the BM aspirate suggested megakaryoblast-like morphological and primary cytochemical staining features, the diagnosis we made was based on a combination of the patient's radiological, morphological, immunological, and clinical features. Overall, the findings were in line with PCM based on the World Health Organization (WHO) classification.[1] The patient received treatment with multiple lines of chemotherapy after the diagnosis was rendered. Pneumonia and respiratory failure happened after 1-week treatment. Chemotherapy continued after the condition improved. Unfortunately, the patient was transferred to the intensive care unit (ICU) due to severe pulmonary infection during the second week of chemotherapy and the disease became difficult to control.

 Discussion



Myeloma plasma cells do occasionally indicate immature or/and plasmablastic cells and cytoplasmic pseudopod, but megakaryoblastic-like cells do not usually constitute the entire plasma cell population as in this patient. This case illustrates the wide morphological variant in PCM and highlights the reason of PCM being taken as a differential diagnosis when one shows typical morphological feature of acute megakaryoblastic leukemia. However, due to the morphologic variant of PCM, the morphology of the myeloma plasma cells is occasionally misleading and is not the only diagnostic standard for PCM. A thorough workup including radiological, morphological, immunological, and clinical features is vital in reaching the accurate diagnosis.

There have been only a few cases of morphological variant of plasma cell neoplasms so far. None of them showed morphological feature of acute megakaryoblastic leukemia. Maryam Pourabdollah et al. showed PCM with plasmablastic morphology mimicking acute leukemia.[4] Moreover, Huifei Liu et al. showed myeloma plasma cells mimicking mature megakaryocytes.[3] We herein describe an elderly man with PCM with megakaryoblast-like morphological features mimicking acute leukemia. Regarding the disease, although our patient presented with the unusual morphological features and confused primary cytochemical staining, the correct diagnosis of PCM was rendered based on radiological, morphological, immunological, and clinical features of the patient. The blasts of the patient were negative for CD41 and CD61, which is/are positive in acute megakaryoblastic leukemia. Thus, acute megakaryoblastic leukemia was excluded out in the differential diagnosis of PCM. Moreover, thoracic puncture biopsy indicated plasma cell neoplasms, thus the correctness of our diagnosis was proved.

It has been reported that plasmablastic type is a rare aggressive morphological variant of plasma cell neoplasms with an adverse prognosis. This feature is connected with several disadvantageous risk parameters, such as extensive bone marrow invasion, higher international staging score, more prone to kidney damage, and cytogenetic abnormalities.[1] We speculated that it was the rare megakaryoblast-like morphological variant mimicking acute leukemia and the molecular cytogenetic abnormalities that resulted in such aggressive course of the disease and unfavorable prognosis. Further cases should be accumulated to explore how to improve the prognosis of the patients.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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