Discussion and Conclusions
Syphilis is a sexually transmitted infection caused by spirochaeteTreponema pallidum. It presents with a wide range of symptoms and sign depending on the stage of the disease. Kidney involvement is rare but a well described manifestation of syphilis with the prevalence ranging from 0.3% to 10% of patients diagnosed with secondary syphilis [5]. It can cause glomerulopathies, tubular pathology and vasculitic lesions in the kidney. The most common glomerular lesion is membranous nephropathy presenting as acute onset nephrotic syndrome [6]. Other syphilis associated glomerular diseases are MCD, FSGS, MPGN, and RPGN.
Rapidly progressive glomerulonephritis (RPGN) is an atypical and very rare presentation of syphilis. Patients present with hematuria, proteinuria, and rapidly increasing serum creatinine over a short period of time. This may or may not be accompanied by other features suggestive of secondary syphilis [2, 4]. The pathogenesis consists of immune complex-mediated glomerular injury as evidenced by the presence of treponemal antigens and antibody to Treponemal pallidum on pathologic examination of renal tissue [7]. Syphilis related glomerulonephritis is diagnosed based on positive serology, histologic evidence of GN with rapid and sustained resolution after treatment with penicillin or the presence of anti-treponemal antibodies or treponemal antigens in the glomerular deposits [8].
Treatment of syphilis-related RPGN includes parenteral penicillin for underlying syphilitic infection [9-10]. There are prior reports describing complete and rapid resolution of renal lesion and normalization of kidney function with penicillin alone [2, 11]. The role of immunosuppressive therapy is unknown, given the paucity of evidence whether it’s beneficial for induction in the acute treatment phase.
Our patient presented with typical clinical feature compatible with RPGN pattern, active urine sediment with rapidly deteriorating renal function. Positive confirmatory treponemal test along with rapid and sustained improvement in renal function after a course of penicillin supports the diagnosis of syphilis related RPGN.
There were several limitations in management of this case, namely lack of renal biopsy to confirm RPGN and lack of serologic tests to rule out other causes of RPGN.
RPGN is a very rare and atypical presentation of syphilis. However, with a global re-emergence of syphilis it’s essential to recognize this atypical renal manifestation of syphilis. This case highlights the significance of considering syphilis as a reversible cause in any patient presenting with a clinical picture suggestive of RPGN.