Clinical characteristics and vascular involvement of Takayasu arteritis versus Kawasaki disease in infants and young children

BACKGROUND: Childhood-onset Takayasu arteritis (c-TAK) in infants and young children often presents with systemic inflammation rather than ischemic symptoms, and its clinical features overlap with intravenous immunoglobulin (IVIG)-resistant Kawasaki disease (KD). To aid in early differentiation, this study compared clinical characteristics and vascular involvement between c-TAK and IVIG-resistant KD in infants and young children. METHODS: This single-center retrospective cohort study included patients under three years old diagnosed with c-TAK or IVIG-resistant KD between June, 2016, and December, 2025. Demographics, clinical presentation, laboratory findings, vascular involvement, immunotherapy, and outcomes were compared between groups. RESULTS: A total of 144 infants and young children were enrolled, including 43 with c-TAK and 101 with IVIG-resistant KD. Compared to the IVIG-resistant KD group, the c-TAK group had a significantly higher proportion of infants (85.7% vs. 29.7%) and females (67.4% vs. 32.7%), longer fever duration (18 [9, 26] vs. 11 [9, 13] days), higher lymphocyte counts (7.09 [5.58, 9.02] vs. 2.92 [2.18, 3.91] × 10⁹/L), and more medium-to-giant coronary artery aneurysms (CAAs; 48.8% vs. 18.8%; all P < 0.001). At the baseline, 76.7% of c-TAK patients received IVIG but experienced recurrent fever. The imaging features in the c-TAK group included vessel wall thickening (95.3%), dilation (79.1%), and stenosis (41.9%). The most commonly involved arteries were the carotid (79.1%), abdominal aorta (69.8%), subclavian (67.4%), and coronary artery (67.4%). Conversely, the IVIG-resistant KD group mainly exhibited CAAs (29.7%). The median follow-up duration was comparable between the two groups (21.0 [11.8, 45.5] vs. 18.0 [12.0, 36.0] months, P = 0.952). By the final follow-up, vascular imaging abnormalities completely resolved in 10.3% of c-TAK patients and 96.9% of IVIG-resistant KD patients. CONCLUSION: In young children, particularly female infants, who present with prolonged fever and a poor response to IVIG, c-TAK should be considered as an important differential diagnosis alongside IVIG-resistant KD. The distribution of vascular involvement, detailed imaging characteristics and regular follow-up may be helpful for the differential diagnosis of these two diseases.