Parrot's pseudoparalysis: a case of congenital syphilis

Abstract

Congenital syphilis is a systemic disease caused by the transplacental transmission of Treponema pallidum, which can severely affect the skeletal system during infancy. Bone involvement is typically characterized by diffuse periostitis and osteochondritis, resulting in an acquired flaccid extremity secondary to severe bone pain, a condition known as ”Parrot’s pseudoparalysis.” This article presents the diagnostic and therapeutic journey of a 2.5-month-old male patient who presented with left arm immobility and a clavicle fracture. Due to the complexity of his clinical and laboratory findings, he was initially misdiagnosed with mechanical trauma and later evaluated for macrophage activation syndrome (MAS). Following referral to our center due to persistent acute-phase reactant elevation and limb immobility, radiological evaluation revealed diffuse periosteal reactions, intramedullary lytic-sclerotic areas in the long bones, and a pathological fracture of the left clavicle. Guided by these specific skeletal findings, serological tests were performed, which returned positive for VDRL and Treponema pallidum-specific antibodies, confirming the diagnosis of early congenital syphilis. After a 14-day course of intravenous aqueous crystalline penicillin G, a dramatic improvement in clinical findings and inflammatory markers was observed, with complete resolution of the pseudoparalysis. Although relatively rare today, congenital syphilis must be retained in the differential diagnosis of infants presenting with unexplained localized edema, pathological fractures, and pseudoparalysis.