An unusual presentation of congenital protein S deficiency: cerebral venous thrombosis with right atrial thrombi in an infant

Abstract

Cerebral venous thrombosis (CVT) is an uncommon but serious cause of pediatric stroke. In infants, it is most often related to dehydration, infection, or perinatal complications, while inherited thrombophilia is a rare underlying factor. Protein S deficiency, a congenital prothrombotic disorder, predisposes to severe thrombotic events from early life, though its presentation with intracardiac thrombosis is exceptional. We report the case of a six-month-old infant admitted with status epilepticus, in whom brain magnetic resonance imaging (MRI) demonstrated extensive CVT involving the superior sagittal, lateral, and straight sinuses. Echocardiography further revealed right atrial thrombi causing functional tricuspid stenosis, an atrial septal defect, and partial thrombosis of the superior vena cava. Etiological work-up confirmed congenital protein S deficiency. The association of CVT with right atrial thrombi in the absence of central venous catheters or structural heart disease is extremely rare. Functional obstruction of the tricuspid valve and the presence of an interatrial communication raised the possibility of paradoxical embolism as a contributing mechanism. The patient was successfully stabilized with anticoagulation alone. This case highlights the severity and unusual presentations of congenital protein S deficiency and underscores the importance of considering inherited thrombophilia in infants with extensive or multifocal thrombosis.