Concurrent Takayasu Arteritis and Microscopic Polyangiitis in a Young Female: A Complex Case of Large- and Small-Vessel Vasculitis.

Vasculitides represent a range of disorders marked by inflammation of blood vessels, often posing significant diagnostic challenges due to their diverse clinical presentations and involvement of multiple organ systems. We present the case of a 26-year-old woman who arrived with hemoptysis and a background of exertional dyspnea, chest pain, and occasional visual disturbances. Initial investigations showed elevated perinuclear anti-neutrophil cytoplasmic antibodies (P-ANCAs) and myeloperoxidase antibodies (MPOs), indicative of microscopic polyangiitis (MPA). Imaging revealed circumferential thickening of the aorta and its branches, occlusion of the left subclavian and common carotid arteries, and ground-glass opacities in the lungs, suggesting the involvement of both large and small vessels. Although the findings suggested both MPA and Takayasu arteritis (TA), differentiating between these conditions was challenging due to overlapping clinical and radiological features. Treatment with prednisone and rituximab initially brought the symptoms under control, but the patient later experienced a relapse, illustrating the complexity of managing simultaneous small- and large-vessel vasculitis. This case highlights the necessity for a comprehensive diagnostic approach and personalized treatment strategies in handling complex vasculitides with multisystem involvement.