IgG4 plasma cell myeloma without clinical evidence of IgG4-related disease: a report of two cases

Figures & data

Figure 1. Serum protein electrophoresis in both patients. Case 1 shows a 34 g/L IgG kappa monoclonal protein running in the beta-2 region and marked suppression of polyclonal gamma globulins. Case 2 shows a 48 g/L IgG lambda monoclonal band running in the beta-1 region, a monoclonal-free lambda light chain band in the beta-2 region, and polyclonal decrease in other immunoglobulins.

Table 1. Summary of immunoglobulin, IgG4 subclass, monoclonal protein and serum-free light chain concentrations for the two cases.

	Reference range	Case 1					Case 2
Date (mm/yy)		7/19^a	9/19	11/19	02/20	06/20 ^b	9/19^a	9/19	10/19	02/20	06/20^c
IgG	6.70–15.20 g/L	22.5 H	16.0 H	16.1H	13.9	10.7	58.3 H	52.8 H	31.1 H	12.7	8.1
IgG1	2.80–8.00 g/L	2.04 L	2.38 L	2.48L	2.62 L	2.45 L	0.625 L	0.602 L	0.740 L	2.93	3.00
IgG2	1.50–5.70 g/L	0.83 L	1.00 L	1.18	1.74	1.92	<0.16 L	0.14 L	0.18 L	0.43 L	0.51 L
IgG3	0.24–1.2 g/L	0.098 L	0.098 L	0.123 L	0.100 L	0.109 L	0.072 L	0.067 L	0.009 L	0.337	0.336
IgG4	0.052–1.25 g/L	16.3 H	13.0 H	11.8H	8.02 H	6.41 H	36.8 H	41.4 H	20.3 H	8.36 H	4.92 H
IgA	0.70–4.00 g/L	0.12 L	0.18 L	0.30L	0.65 L	0.57 L	0.19 L	0.17 L	0.23 L	0.33
IgM	0.40–2.3 g/L	0.25 L	0.31 L	0.28L	0.25 L	0.18 L	<0.05 L	0.08 L	0.08 L	0.14
M protein by SPEP	0 g/L	26.9 H	19.1 H	17.5H	13.7 H	7.3 H	50.0 H	40.1 H	32.9 H	10.6 H	4.0 H
Serum-free light chain kappa	3.3–19.4 mg/L	361.1 H	190.0 H	237.0 H	98.7 H	56.2 H	15.1	8.7	8.9		15.1
Serum-free light chain lambda	5.7–26.3 mg/L	3.9 L	8.2	11.4	12.2	10.8	5460 H	874.0 H	471.0 H		45.5 H
Serum-free light chain ratio (involved/uninvolved)	0.26–1^(kappa/lambda).65	92.6 H	23.2 H	20.8 H	8.1 H	5.2 H	361.6 H	100.4 H	52.9 H		0.33

Notes: IgA and IgM were measured by nephelometry while IgG and IgG subclasses were measured by liquid chromatography tandem mass spectrometry. Abbreviations: H, high; IgA, immunoglobulin A; IgG, immunoglobulin G; IgM, immunoglobulin M; L, low; SPEP, serum protein electrophoresis.

^aAt diagnosis.

^bAfter 13 cycles of lenalidomide and dexamethasone treatment.

^cAfter eight cycles of cyclophosphamide, bortezomib and dexamethasone treatment.

Figure 2. Representative photomicrographs of marrow trephine biopsy in Case 2: (A) H&E showing subtotal replacement of the cellular marrow by plasma cells (200×). (B) Immunohistochemistry for Lambda showing lambda-restriction (200×). (C) Immunohistochemistry for IgG and (D) IgG4 showing the majority of plasma cells staining positive for both IgG and IgG4 (400×). On-slide negative and positive controls showed appropriate staining pattern (images not shown).

Data availability

The datasets during and/or analyzed during the current study available from the corresponding author on reasonable request.