Detection of a Lymphoproliferative Disorder With Suspected Scattergram Analysis Using the Mindray BC-6800 Plus Automated Hematology Analyzer: A Case Report

Abstract

A 50-year-old Caucasian woman was admitted to the Hematology Department complaining of abdominal distension and early satiety for 8 months, accompanied by involuntary weight loss of 23 kg over the past year. Her medical history revealed thalassemia, and she had no current or past history of smoking or alcohol consumption. Initial examination revealed splenomegaly (25 cm).

Laboratory analysis showed a white blood cell count of 5.00 × 10⁹/L (normal reference range: 4.50–11 × 10⁹/L), a hemoglobin level of 65 g/L (normal reference range: 115–135 g/L), a platelet count of 135 × 10⁹/L (normal reference range: 150–450 × 10⁹/L), an absolute neutrophil count of 1.39 × 10⁹/L (normal reference range: 1.80–7.70 × 10⁹/L), an increase in cell damage indices (lactate dehydrogenase = 1094 U/L; normal reference range: 208–450 U/L), and inflammation indices (C-reactive protein = 4.14 mg/dL; normal reference range: 0–1 mg/dL).

Liver and coagulation values were within normal limits, with a high serum level of β-2-microglobulin (β2M = 4586 ng/mL; normal reference range: 900–2000 ng/mL).

The blood count analysis performed with the BC-6800 Plus hematology analyzer (Mindray, Medical System) raised the suspicion of a lymphoproliferative disorder based on the characteristic pattern in the scattergram DIFF diagram typical of this type of hematologic disorder (Figure 1A,B). Smear examination using the MC-80 automated digital cell morphology analyzer (Mindray, Medical System) revealed the presence of cells with immature features (Figure 2). We observed about 13% immature cells, which was confirmed by expert hematologists.

Given the combination of anemia, neutropenia, thrombocytopenia and immature cells, a provisional diagnosis of acute leukemia was made. However, subsequent flow cytometric analysis performed on peripheral blood specimen, surprisingly revealed absence of blasts (CD34+) but an immunophenotype consistent with a clonal B lymphoproliferative disorder, CD5+. In addition, the negativity of CD23 and CD200 markers led to the hypothesis of mantle cell lymphoma (MCL), pending further histologic examination.

Immunohistochemical examination of the lymphoma cells from the bone marrow biopsy revealed positivity for CD20 and CD5 and negativity for CD23, CD10, and cyclin D1. In addition, the absence of t(11;14) (CCND1-IgH) detected by FISH confirmed the diagnosis of CD5+ splenic marginal zone lymphoma (SMZL). Hematopoietic cellularity shows remarkable changes in megakaryocytes with increased numbers with isolated forms and loose clusters, some with hyperlobulated nuclei, and an increased eosinophil lineage. These findings and the presence of the CALR mutation are consistent with a myeloproliferative neoplasm that is partially obscured by the associated lymphoproliferative disorder, which is quantitatively predominant. Reticulin staining shows a diffuse increase in the argentophilic network, slightly heterogeneous, in the presence of an abundant lymphoid infiltrate associated with a myeloproliferative neoplasm (MF1-2).

In light of the dual concomitant diagnosis of SMZL and idiopathic myelofibrosis, and the need to initiate a specific therapy for the lymphoproliferative disorder, the patient has started a fist line therapy with rituximab in order to reduce the bone marrow infiltrate and the splenomegaly. Based on the response regarding splenomegaly and anemia, the therapeutic plan for myelofibrosis will be evaluated.

The rarity of this case lies in the cells observed in the blood smear, which had blast cell characteristics and were completely different from typical SMZL cells, which are small to medium-sized mature B cells with round or oval nuclei and condensed chromatin, basophilic cytoplasm and typical unequal membrane protrusions (villi) known as villous cells [1]. It is noteworthy that the three-dimensional lymphocyte arrangement on the scattergram DIFF diagram initially suggested a lymphoproliferative disorder.

The literature indicates that 75% of SMZL patients have lymphocytosis with characteristic villous cells, while cytopenias are found in only 25% of cases [2]. In this case, the partial replacement of the hematopoietic cellularity by the presence of an abundant (80%) lymphoid infiltrate with an interstitial, nodular, and diffuse pattern could be the cause of the cytopenia. The lack of typical morphology, as well as CD5 positivity in such cases, can pose diagnostic challenge [3]. Careful correlation of morphology with cytogenetics, flow cytometry and molecular findings can help confirm the diagnosis of this rare type of lymphoproliferative disorder.

In order to develop a more accurate screening algorithm, it is essential to study more cases.

Future studies should further investigate the diagnostic utility and potential clinical application of the Mindray BC6800 Plus morphologic RUO parameters to improve the early diagnosis of lymphoproliferative disorders, especially as they are inexpensive and available to all laboratories.