The patient was a 62-year-old Chinese man who was admitted to another hospital on October 9, 2019, due to abdominal distension and intermittent left lower abdominal pain for one week. Physical examination revealed abdominal distension and spleen rib under 6 cm. Hematological investigations showed a significantly increased white blood cell count and moderate anemia (white blood cell count, 133.82 × 109/l; red blood cell count, 2.30 × 1012/l; hemoglobin level, 76 g/l and platelet count, 105 × 109/l). Biochemical tests indicated a marked elevation of globulin. Monoclonal bands were found by serum immunofixation electrophoresis. Abdominal ultrasonography revealed a large spleen. Molecular genetic studies were performed to screen BCR/ABL1, PDGFRA, PDGFRB, and FGFR1 rearrangements and point mutations in CSF3R, JAK2, CALR, and MPL, and the results were all negative. Bone marrow plasma cells accounted for 2%. The patient was diagnosed with “CNL and monoclonal gammopathy of undetermined significance (MGUS)” at this hospital and treated with splenectomy and hydroxyurea. After these treatments, the patient’s abdominal distention was reduced, and the white blood cell count dropped to 32.21 × 109/l. On December 6, 2019, the patient was admitted to the emergency intensive care unit (ICU) of our hospital due to cough for more than half a month, aggravation with shortness of breath for one week, and confusion for 7 hours. A chest radiograph showed bilateral pneumonia. His condition improved after endotracheal intubation and anti-infective treatment. And then he was transferred to the hematology department for further diagnosis and treatment.
Routine blood tests revealed a hemoglobin level of 47 g/l (normal range, 130–175 g/l), a red blood cell count of 1.02 × 1012/l (normal range, 4.30–5.80 × 1012/l), a white blood cell count of 75.76 × 109/l (normal range, 3.50–9.50 × 109/l) and a platelet count of 70 × 109/l (normal range, 150–350 × 109/l). A peripheral blood film (1% neutrophilic myelocytes, 2% neutrophilic metamyelocytes, 65% band-stage neutrophils, 26% segmented neutrophils, 3% lymphocytes, and 3% monocytes) indicated leukocytosis with an increased number of segmented and band-stage neutrophils with clear cytoplasmic toxic granules and Döhle bodies. A small number of myelocytes and an occasional blast were noted; however, basophilia or eosinophilia were not observed (Fig. 1A). Furthermore, the patient's peripheral blood neutrophil alkaline phosphatase (NAP) score was 293 (normal range, 40–80).
Bone marrow aspiration demonstrated notably hypercellular marrow with marked granulocytic proliferation, predominantly consisting of band-stage and segmented neutrophils, with clear cytoplasmic toxic granules and Döhle bodies. Erythroid and megakaryocytic cell levels were decreased. However, the morphology was normal. In addition, the myeloid:erythroid ratio was 16.7:1, and there was no increase in the proportion of basophils and eosinophils (Fig. 1B). A trephine biopsy of the bone marrow demonstrated similar results, and there was no increase in the number of reticulin fibers. Flow cytometry analysis was consistent with marked myeloid hyperplasia without an increase in the number of blasts or monocytes. However, it was difficult to distinguish CNL from LR based on the above findings. The diagnosis should be confirmed by demonstrating neutrophil clonality. Therefore, cytogenetic and molecular studies were conducted on the patient.
Conventional cytogenetic analysis revealed a normal karyotype [46, XY (20 cells)] and an absence of the Philadelphia (Ph) chromosome. Furthermore, molecular biology investigations demonstrated no mutations in the CSF3R gene, negativity for p210 BCR/ABL1, p230 BCR/ABL1 and p190 BCR/ABL1 fusion proteins, an absence of the JAK2V617F mutation, and no mutations in PDGFRA/PDGFRB. Furthermore, using whole-exon sequencing (WES), we did not find any mutations in CSF3R, SETBP1, ASXL1, TET2, SRSF2, SF3B1, ZRSR2, or U2AF1. Therefore, the diagnosis of CNL could not be established. Meanwhile, it is necessary to find out the reason and the explanation for the significantly increased neutrophils counting of the patient.
The biochemical examination showed that the creatinine level was 147.04 µmol/l (normal range, 45–133 µmol/l) and uric acid was 567 µmol/l (normal range, 238–506 µmol/l). The serum albumin and globulin levels were 21.43 g/l (normal range, 40.0–55.0 g/l) and 65.34 g/l (normal range, 20–40 g/l), respectively, indicating a reversal of the albumin/globulin ratio (0.33; normal range, 1.2–2.4). Serum immunoglobulin analysis revealed immunoglobulin G (IgG) at 55.7 g/l (reference values: 7.51–15.6 g/l), IgA at 0.46 g/l (reference values: 0.82–4.53 g/l), and IgM at 0.26 g/l (reference values: 0.46–3.04 g/l). Serum protein electrophoresis was positive for a monoclonal spike (M-spike) of 67.2% in the beta region. Serum immunofixation electrophoresis indicated the presence of monoclonal bands in the IgG and kappa lanes. A computed tomography (CT) scan revealed an osteolytic lesion in the left ilium. Based on these findings, MM was highly suspected. Therefore, bone marrow aspiration and biopsy were performed for the pathological diagnosis. Bone marrow aspiration from the right posterior iliac revealed only a mild increase in plasma cells (2.5% plasma cells of the ANC) (Fig. 1B), but aspiration from the left posterior iliac revealed a moderate increase in plasma cells (18.5% plasma cells of the ANC) (Fig. 1C), and clusters of distributed plasma cells (Fig. 1D) could be easily seen. Bone marrow biopsy revealed markedly hypercellular marrow and clusters of distributed plasma cells. Immunohistochemical staining from left posterior iliac bone was positive for CD38, CD138 and CD56. Kappa and lambda light chain in situ hybridization showed the monoclonal expression of the kappa light chain, which was in accordance with plasmacytoma (Fig. 2). Flow cytometry of bone marrow aspirates revealed that the proportion of atypical cells was 8.6%. These cells exclusively expressed kappa chains, showed strong CD38 and CD138 expression and simultaneously expressed CD117 and CD56. All these findings led to the diagnosis of MM.
The patient had intermittent pain in the left lower abdomen during the course of the disease. Abdominal CT showed marked thickening of the middle intestinal wall of the left descending colon and narrowing of the intestine (Fig. 3A). At first, MM was suspected to have extramedullary invasion. However, Tumor markers, including CEA (340.47 ng/ml; normal range, 0.15–9.7 ng/ml), CA199 (797.80 U/ml; normal range, < 35.00 U/ml) were significantly elevated. Colonoscopy showed a cauliflower mass in the colon (Fig. 3B), and biopsy showed adenocarcinoma of the colon without plasma cell involvement (Fig. 3C). At this point, the diagnosis of a primary colon tumor was clear.