Table 2 Results from flow cytometry analysis of plasma cells in bone marrow samples from individuals with positive screening for light-chain monoclonal gammopathy.

From: The significance of free light-chain ratio in light-chain monoclonal gammopathy of undetermined significance: a flow cytometry sub-study of the iStopMM screening study

Characteristic

LC-MGUS

p-value

LC-MGUS

LC-SMM

LC-MM

p-value

SPM

Clonal PC not detected

Clonal PC detected

n

13

15

—

28

24

8

—

1

Age, median (range)

70 (54–87)

59 (43–77)

<0.05

63 (43–87)

70 (47–87)

67 (48–89)

0.25

72

Sex, n male (%)

8 (61.5%)

12 (80.0%)

0.41

20 (71.4%)

16 (66.7%)

7 (87.5%)

0.53

0 (0%)

eGFR (mL/min/1.73 m2), median (IQR) [range]

67.6 (45.1–77.3)

78.4 (75.6–91.5)

<0.01

76.1 (67.2–82.0)

71.0 (57.5–84.8)

69.5 (51.7–96.3)

0.74

60.5

[11.8–86.8]

[66.7–110.8]

[11.8–110.8]

[27.5–99.0]

[50.8–98.5]

Kappa inv., n (%)

12 (92.3%)

12 (80.0%)

n.a.

24 (85.7)

11 (45.8%)

6 (75.0%)

n.a.

1 (100%)

 FLC ratio, median (IQR) [range]

2.13 (1.94–2.54)

4.52 (3.74–8.16)

<0.001

3.15 (2.15–4.76)

26.5 (23.0–41.6)

163 (130–229)

<0.001

13.3

[1.49–4.98]

[2.78–41.5]

[1.49–41.5]

[7.70–68.1]

[109–347]

 Kappa FLC (mg/L), median (IQR) [range]

62.5 (42.2–82.4)

59.7 (47.1–99.4)

0.41

60.9 (45.0–96.3)

304.6 (162.8–524.9)

1225.2 (1090.3–2301.5)

<0.001

222.9

[19.9–100.4]

[43.9–322.2]

[19.9–332.2]

[77.7–1061.6]

[890.8–2778.3]

Lambda inv., n (%)

1 (7.69%)

3 (20.0%)

n.a.

4 (14.3%)

13 (54.2%)

2 (25.0%)

n.a.

0 (0%)

 FLC ratio, median (IQR) [range]

0.774

0.207 (0.123–0.222)

n.a.

0.222 (0.165–0.372)

0.0560 (0.0295–0.0825)

0.0110 (0.00588–0.0161)

n.a.

—

[0.0386–0.238]

[0.0386–0.774]

[0.0141–0.348]

[0.000783–0.0212]

 Lambda FLC (mg/L), median (IQR) [range]

19.0

140.4 (101.4–214.0)

n.a.

101.4 (51.5–177.2)

349.2 (145.6–464.8)

5828.5 (3313.3–8343.8)

n.a.

—

[62.3–287.5]

[19.0–287.5]

[68.1–742.5]

[798.0–10859.0]

I/U FLC ratio, median (IQR) [range]

2.08 (1.78–2.53)

4.69 (3.98–8.86)

<0.001

3.46 (2.15–4.86)

24.6 (13.6–39.0)

163 (122–270)

<0.001

13.3

[1.29–4.98]

[2.78–41.5]

[1.29–41.5]

[2.87–70.8]

[47.2–1278]

Flow cytometry analysis of BM

 % PC, median (range)

0.186 (0.0413–0.617)

0.522 (0.132–5.22)

<0.01

0.300 (0.0413–5.22)

2.31 (1.19–3.27)

3.69 (1.02–17.0)

<0.001

0.539

 Clonal PC detected, n (%)

0 (0%)

15 (100%)

n.a.

15 (53.6%)

24 (100%)

8 (100%)

<0.001

1 (100%)

 % clonal PC (of nucleated cells), median (range)

0 (0%)

0.249 (0.0623–5.17)

n.a.

0.0718 (0.00–5.17)

2.09 (0.319–8.51)

3.66 (0.977–16.9)

<0.001

0.0676

 % clonal PC (of PC), median (range)

0 (0%)

64.2 (35.6–99.0)

n.a.

38.5 (0.00–99.0)

92.7 (48.3–99.3)

99.0 (91.1–99.9)

<0.001

12.5

 cyIgLC PC ratioa, median (IQR) [range]

1.62 (1.78–2.53)

4.83 (3.36–17.0)

<0.001

2.44 (1.66–5.38)

25.3 (18.8–70.0)

184 (54.7–334)

<0.001

2.20

[1.12–2.36]

[2.18–155]

[1.12–155]

[2.70–210]

[33.3–943]

  1. The table categorizes individuals based on their diagnosis at the time of flow cytometry analysis. The left side compares individuals with light-chain monoclonal gammopathy with undetected versus detected clonal plasma cells, while the right side compares different plasma cell disorders.
  2. LC light-chain, MGUS monoclonal gammopathy of undetermined significance, SMM smoldering multiple myeloma, MM multiple myeloma, SPM solitary plasmacytoma with minimal marrow involvement, eGFR estimated glomerular filtration rate, FLC Free light-chain, I/U involved/uninvolved, PC plasma cell, cyIgLC cytoplasmic immunoglobuling light-chain, BM bone marrow.
  3. aRatio of kappa and lambda expressing plasma cells (higher number over lower).
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