PC1210: Abusive Injuries or Medical Mimicker? 3-month-old Admitted with Multiple Long Bone Fractures

Introduction: Cases of congenital syphilis have steadily increased over the last decade. Presenting symptoms can be varied, making the disease challenging to diagnose. We present a case of a 3-month-old infant admitted with multiple fractures concerning for physical abuse but was ultimately diagnosed with congenital syphilis.

Case Description: A 3-month-old previously healthy, full-term male presented to the emergency department due to concerns for left arm pain. Caregivers reported the infant had decrease use of his left arm compared to the right shortly after birth. Over the last two days the patient developed swelling and pain with manipulation. No history of trauma. Physical exam was notable for an alert infant with no significant cutaneous findings, including bruising. Left upper extremity demonstrated tenderness with palpation, decreased tone (“floppy wrist”), and no spontaneous movement. Skeletal survey revealed periosteal reactions bilaterally around the humerus, radius, ulna, femurs, and tibias. Healing distal metaphyseal fractures were noted on the right radius and ulna, right tibia and fibula, and left femur. Nonaccidental trauma workup, including head computed tomography and ophthalmologic exam, was negative. Social work was consulted and a report to child protective services was completed. The patient was admitted for further evaluation.

The patient was evaluated by the child abuse pediatric team the following day. The pattern, distribution and characteristics of the radiographic findings coupled with the poor left upper extremity tone expanded the differential diagnosis and additional tests were ordered. The patient’s rapid plasma reagin (RPR) titer was elevated to 1:1024 and pediatric infectious disease was consulted. Ultimately, he was diagnosed with congenital syphilis and started on a 10-day course of penicillin G followed by a dose of benzathine. A repeat skeletal survey was negative for abnormalities unrelated to the expected sequela of congenital syphilis.

Discussion: Between 2015 and 2019, there has been a 291.1% relative increase in the rate of congenital syphilis diagnoses in the United States. Bone abnormalities may be the only symptom of underlying disease. Radiographic abnormalities related to congenital syphilis most often occur in the long bones and are characteristically symmetric. This includes bilateral periosteal reactions of multiple long bones and metaphyseal changes that appear serrated and/or may have a ‘moth eaten’ appearance. This is in contrast with the more frequent classic metaphyseal lesions observed in abusive injuries (“bucket-handle” or “corner fractures”) and limited periosteal reactions. Long bone abnormalities related to congenital syphilis may result in painful pathologic fractures that limit extremity movement, leading to apparent paralysis (pseudo-paralysis of Parrot). These phenomena were seen in our patient and guided the team’s diagnostic workup.

Conclusion: Congenital syphilis should be considered when an infant presents with bone abnormalities. This case highlights the importance of keeping a broad differential when evaluating potential abusive injuries.