Atypical Pediatric-Onset Behçet's Disease Presenting With Superior Vena Cava Thrombosis in an Adolescent Male: A Case Report.

Behçet's disease is a chronic, relapsing multisystem vasculitis known for its highly variable clinical spectrum. We report the case of an 18-year-old male who presented with progressive headache and facial swelling. Imaging revealed extensive thrombosis involving the dural venous sinuses, superior vena cava, and left brachiocephalic vein. Despite the absence of ocular involvement or genital ulcers, a diagnosis of Behçet's disease was established based on recurrent oral ulcers, cutaneous findings, vascular thrombosis, and a positive pathergy test, fulfilling the International Criteria for Behçet's Disease. The patient was treated with corticosteroids, azathioprine, colchicine, and rivaroxaban, resulting in clinical and radiologic improvement. This case highlights a rare and aggressive vascular manifestation of Behçet's disease in an adolescent, emphasizing the need for early diagnosis and immunosuppressive management to prevent long-term complications.