[Rash and nephrotic syndrome: consider syphilis].

Introduction: Kidney disease is among the clinical manifestations of secondary syphilis, as this case report shows.

Observation: During serologically confirmed secondary syphilis, a 63-year-old man developed a nephrotic syndrome diagnosed after biopsy as membranous nephropathy.

Discussion: Membranous nephropathy is an immunological complication of secondary syphilis. Recovery usually follows treatment. It is often associated with signs that may erroneously suggest connective tissue disease.