Membranous nephropathy with systemic light-chain amyloidosis of remission after rituximab therapy: A case report

Table 1 Laboratory data before kidney biopsy

Blood examination		Urinary examination
ALB (g/L, 35–55)	18.3	RBC (cell/HPF, 0–4.5)	65.3
SCr (μmol/L, 35–106)	97.3	Proteinuria (g/24 h, < 0.16)	17.84
eGFR (mL/min/1.73 m2)	78.9	mALB/Cr (mg/mmoL Cr, < 3.7)	560.55
UA (μmol/L, 150–420)	465	α1-MG (mg/dL, < 1.25)	41.1
CHO (mmol/L, < 5.2)	7.68	β2-MG (μg/L, 0–150)	16573.54
TG (mmol/L, < 1.7)	3.64	IgG-lambda-M protein (neg.)	Positive
IgG-lambda-M protein (g/L, neg.)	0.9
FLC-lambda (mg/L, 5.71–26.3)	28.1	Hepatitis serology	-
FLC-kappa/lambda (0.26–1.65)	0.61	Anti-HBs (mIU/mL, < 10)	721
Anti-PLA2R (RU/mL, 4–20)	374.3	Anti-HBc (COI, > 1)	0.03
IgG (mg/dL, 694–1620)	357	HBV-DNA (IU/mL, < 100)	< 0.01
IgA (mg/dL, 68–378)	53.9	Anti-HCV (neg.)	Negative
C3, C4	Normal	HIV Ag/Ab (neg.)	Negative
RF (IU/mL, < 20)	20.2
Autoantibodies (ANA, MPO, ANCA, anti-SSA, anti-SSB)	Negative	Hematology	-
Coagulation	Normal	WBC (×109 cell/L, 3.5–9.5)	9.6
BNP, hsTnI	Normal	HB (g/L, 130–175)	123

ALB: Albumin; Anti-PLA2R: Phospholipase A2 receptor antibody; ANA: Antinuclear antibody, anti-SSA: Anti-Sjögren's-syndrome-related antigen A; Anti-HBs: Hepatitis B surface antibody; Anti-HBc: Hepatitis B core antibody, anti-HCV: Hepatitis C virus antibody; α1-MG: α1-microglobulin; BNP: B-type natriuretic peptides; β2-MG: β2-microglobulin; CHO: Cholesterol; C3: Complement 3; C4: Complement 4; eGFR: Estimated glomerular filtration rate; FLC: Free light-chain; hsTnI: High-sensitive troponin I; HIV Ag/Ab: Human immunodeficiency virus antigen/antibody; HBV: Hepatitis B virus; Hb: Hemoglobin; IgA: Immunoglobulin A; IgG: Immunoglobulin G; MPO-ANCA: Myeloperoxidase antineutrophil cytoplasmic antibody; RF: Rheumatoid factor; RBC: Red blood cell; SCr: Serum creatinine; TG: Triglyceride; UA: Uric acid; WBC: White blood cell.

Table 2 Literature review of membranous nephropathy with amyloidosis

Ref.	No.	Patient	Country	Age	Sex	Proteinuria (g/d)	Scr (μmol/L)	ALB (g/L)
Kuroda et al[9], 2012	6		Japan	NA	NA	NA	NA	NA
Lu et al[10], 2017	1	Patient 1	China	64	M	10.06-10.52	77.35	26.7
Li et al[11], 2020	4	Patient 4	China	74	F	11.26	118	26.5
		Patient 5	China	61	F	2.44	76	22.3
		Patient 6	China	79	M	7.92	541.8	24.7
		Patient 7	China	61	F	3.89	70.2	31.4
Morel et al[12], 2022	1		France	56	M	UPCR 522 mg/mmol (after 6 years)	eGFR 78.9 mL/min/1.73 m2 (after 6 years)	23 (after 6 years)
Wang et al[13], 2022	1		China	39	M	8.01	95.3	13.1
The present case	1		China	48	M	17.84	97.3	18.3

ALB: Albumin; eGFR: Estimated glomerular filtration rate; F: Female; M: Male; No: Number; NA: Not available; SCr: Serum creatinine; UPCR: Urine protein/creatinine ratio.

Table 3 Summary of outcomes of reported studies

Ref.	PLA2R	Type of amyloidosis	Affected organs	Diagnosis of amyloidosis	Treatment	Renal outcomes
Kuroda et al[9], 2012	NA	Reactive AA (related to RA)	Renal	Renal biopsy	NSAIDs+DMARD	NA
Lu et al[10], 2017	Positive	Nonhereditary ApoA-1	Renal	Biopsy of abdominal fat, rectal mucosa, bone marrow and renal	GC+cyclosporine	Remission
Li et al[11], 2020, Patient 4	Positive	ALECT2	Renal	Renal biopsy, MS	Support therapy	Maintenance
Li et al[11], 2020, Patient 5	Suspicious Positive	ALECT2	Renal	Renal biopsy, MS	Support therapy	Maintenance
Li et al[11], 2020, Patient 6	Positive	ALECT2	Renal	Renal biopsy, MS	GC+CTX	Remission
Li et al[11], 2020, Patient 7	Suspicious Positive	ALECT2	Renal	Renal biopsy, MS	Chelation therapy (due to mercury poisoning)	Maintenance
Morel et al[12], 2022	Negative	Secondary AL (related to WM)	Retro-peritoneal, mesent-eric adipose tissue, bone marrow, bladder, cardiac and renal	Biopsy of retro-peritoneal, mesenteric adipose tissue, bone marrow, bladder, cardiac and renal	ASCT+RTX	Complete remission (after 2 yr)
Wang et al[13], 2022	Positive	Primary AL	Renal	Renal biopsy	Support therapy	NA
The present case	Positive	Primary AL	Renal	Renal biopsy	RTX+GC+CyBorD	Complete remission (after 21 mo)

AA: Amyloid A; ApoA-1: Apolipoprotein A-1; ALECT2: Leukocyte chemotactic factor 2; AL: Amyloid light chain; ASCT: Autologous stem cell transplantation; CTX: Cyclophosphamide; CyBorD: Cyclophosphamide, bortezomib, and dexamethasone; DMARD: Disease-modifying antirheumatic drug; GC: Glucocorticoid; MS: mass spectrometry; NA: Not available; Negative: Negativetive; NSAIDs: Non-steroidal anti-inflammatory drugs; PLA2R: Phospholipase A2 receptor; Positive: Positivetive; RA: Rheumatoid arthritis; RTX: Rituximab; WM: Waldenström macroglobulinemia.