Clinicopathological study of mixed cryoglobulinemic glomerulonephritis secondary to hepatitis B virus infection

Abstract Background Cryoglobulinemic glomerulonephritis (CryoGn) caused by hepatitis B virus (HBV) infection was rarely reported. Our study aimed to investigate the clinical features, renal pathology findings, and prognosis in patients with HBV related CryoGn. Methods This was a retrospective study including seven Chinese patients with HBV related CryoGn in a tertiary referral hospital from April 2016 to March 2019. The clinical and pathological data were collected and analyzed. Results Age at renal biopsy was 47 ± 12 years, with female/male ratio 3/4. Urine protein was 5.6 (3.0, 6.6) g/d and five cases presented with nephrotic syndrome. The baseline eGFR was 23.5 (20.2, 46.3) ml/min per 1.73m2. The extrarenal manifestations included purpura (n = 6), arthralgia (n = 1), peripheral neuropathy (n = 1), and cardiomyopathy (n = 1). Six cases had type II cryoglobulinemia with IgMκ, the other one had type III. The median cryocrit was 4.0 (1.0, 15.0) %. Renal pathologic findings on light microscopy: endocapillary proliferative glomerulonephritis (Gn) (n = 3), membranoproliferative Gn (n = 3), and mesangial proliferative Gn (n = 1). On immunofluorescence microscopy, the predominant type of immunoglobulin deposits was IgM (n = 5). HBsAg and HBcAg deposits were found in one case. Ultrastructural studies showed granular subendothelial and mesangial electron-dense deposits in all patients and microtubules in one case. All patients received antiviral medications. They were given corticosteroid alone (n = 2) or combined with cyclophosphamide (n = 4) or mycophenolate mofetil (n = 1). Two patients received plasmapheresis. The median follow-up time was 18 (6, 37) months. Four patients got remission, two patients died of pneumonia, and one progressed to end-stage renal disease (ESRD). At endpoint of follow-up, 24hUP was 2.1 (0.8–5.2) g/d, and eGFR was 55.3 (20.7, 111.8) ml/min per 1.73m2. The median cryocrit decreased to 1.0 (0, 5.75) %. Conclusions The etiology of mixed CryoGn should be screened for HBV infection. Endocapillary proliferative Gn and membranoproliferative Gn were the common pathologic patterns. Diagnosis and treatment in early stage benefit patients’ renal outcomes. Immunosuppressive therapy should be considered for severe renal disease, based on efficient antiviral therapy.