#6605 A CASE REPORT OF MEMBRANOUS NEPHROPATHY SECONDARY TO SYPHILIS: A STEROID-RESPONSIVE DISEASE?
Authors: Maso Vittorio DI , Yazbek Ahmad , Perencin Brigitta , Colli Claudia , Oivo Elisa , Zacchi Alberto , Zanconati Fabrizio , Bianco Francesco 
Published: June 2023

Abstract

Background and Aims
Membranous Nephropathy (MN) is among the most common forms of nephrotic syndrome in the adults. MN in adults is most often primary (75-80%) and caused by circulating autoantibodies against podocyte antigens being PLA2R the most important target. In the remaining 20-25% of cases, the MN lesion is associated with various disorders, including infections, autoimmune diseases, thyroiditis, malignancies, and the use of certain drugs. Syphilis is a chronic bacterial infection caused by Treponema Pallidum that can present in the primary, secondary or tertiary forms. Kidneys can be involved during either the secondary or the tertiary phase and the most frequent clinical presentation is nephrotic syndrome underlying membranous nephropathy. Here, we present the case of a 47-year-old man who developed rapidly progressive acute kidney injury, nephrotic syndrome and a blotchy diffuse macular rash secondary to Treponema Pallidum infection.

Method
Data review and collection of clinical records, kidney biopsy evaluation, treatment and outcomes description.

Results
A 47-year-old man presented to our hospital complaining about asthenia and dizziness. He reported recent use of both antinflammatory drugs and antibiotics to treat an anal fissure. His past medical history was notable for previous drug abuse and alcohol consumption. Physical examination highlighted peripheral edema and a diffuse macular rash. Serum analysis showed serum creatinine of 2.06 mg/dL, urea 84 mg/dL, haemoglobin 13.8 g/dL, albumin 4 g/dL and protein/creatinine ratio of 17741 mg/g; urinary dipstick was positive for haemoglobinuria and proteinuria. Urine collection revealed 22 g proteins/24h. Kidney ultrasound showed normal kidneys with a preserved cortico-medullary differentiation and thickness. In the next days kidney function worsened (serum creatinine 3 mg/dL and urea 100 mg/dL) and daily proteinuria reached a peak of 35 g/24h. A complete panel of antibodies was searched. IgG4 against PLA2R were negative. ANA, ENA and ANCA were absent, C3 and C4 were in the normal range. Serologic testing for HBV, HCV and HIV were negative. Empiric steroid therapy with prednisone 1 mg/kg/day was started obtaining a rapid improvement in terms of proteinuria and kidney function (Fig. 1), the cutaneous rash fainted. Kidney biopsy was performed and demonstrated a membranous nephropathy. Serologic testing for syphilis revealed positive TPHA (titer, 1:2560; normal value, &lt;1:80) and a positive Venereal Disease Research Laboratory test (VDRL) (titer, 1:32; normal value, &lt;1:2). The presentation suggested the diagnosis of anti-PLA2R negative membranous nephropathy secondary to systemic syphilis. Because of the serious clinical manifestation and the unknown duration of the infection we decided to treat the patient with Benzathine penicillin G 2.4 million units administered as three doses at one week intervals (Schön & Bertsch, 2016). Oral steroid was maintained at a dose of 1mg/kg/body weight and descalation started after 30 days. The proteinuria also improved with a reduction in the 24-hour collection from 30 g to 200 mg and serum creatinine went back to normal. Clinical course according to treatment phases are summarized in Fig. 1.

Conclusion
As far as we know, this is the first case of PLA2R negative membranous nephropathy secondary to syphilis. Although, antibiotic therapy is pivotal in syphilis treatment, our patient showed a fast improvement of kidney function, proteinuria and fainting of the cutaneous erythema after steroid therapy and before starting antibiotic therapy. This suggested the possible role of steroids in treatment of secondary T. Pallidum infection complicated by anti-PLA2R negative membranous nephropathy. Further researches are needed to better define the possible role of steroids in the context of an infective but immune-complex mediated nephropathy.