Takayasu Arteritis in a Child with Chronic Active Proctitis of Unspecified Etiology: A Case Report with Diagnostic Challenges and Literature Review.

Takayasu arteritis (TAK) is a rare large-vessel vasculitis in children. A 14-year-old girl presented with intermittent fever, elevated inflammatory markers (C-reactive protein up to 117.63 mg/L and erythrocyte sedimentation rate of 93 mm/h), and computed tomography angiography demonstrating diffuse wall thickening of the aortic arch and its major branches. She had a previous diagnosis of ulcerative colitis; however, colonoscopy and biopsy revealed severe chronic active proctitis with glandular architectural irregularity and occasional cryptitis, but without crypt abscesses or granulomas, and the overall findings were insufficient to confirm ulcerative colitis or intestinal Behçet's disease. Behçet's disease was excluded because of the absence of oral or genital ulcers, ocular lesions, and skin manifestations. The patient met both the 2010 EULAR/PReS/PRINTO and 2022 ACR/EULAR classification criteria for TAK. Initial treatment with prednisone and adalimumab induced remission. A disease flare in June 2025 (C-reactive protein, 53.43 mg/L; erythrocyte sedimentation rate, 50 mm/h; and worsening carotid artery wall thickening) was controlled by increasing the prednisone dose and adding tocilizumab. At the 10-month follow-up, she remained asymptomatic, with stable vascular findings. This case highlights the importance of applying rigorous diagnostic criteria to avoid overdiagnosis of Behçet's disease in children with TAK and nonspecific intestinal inflammation.