Comparison of Clinical and Laboratory Findings Between Skin-limited and Cutaneous-Articular Immunoglobulin A Vasculitis in Children.

OBJECTIVE: This study aimed to compare the clinical and laboratory characteristics of skin-limited and cutaneous-articular immunoglobulin A vasculitis (IgAV) in children without gastrointestinal or renal involvement, and to assess whether C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and antinuclear antibodies (ANAs) help differentiate these phenotypes. METHODS: In this single-center retrospective study, children diagnosed with IgAV were identified from electronic medical records. Patients were classified as having skin-limited or cutaneous-articular IgAV according to standardized clinical criteria. Demographic features, rash patterns, acute-phase reactants, including CRP and ESR, complete blood count parameters, complement levels, and ANA were compared between the 2 phenotypes. RESULTS: A total of 256 children were included (102 skin-limited, 154 cutaneous-articular). Demographic characteristics, rash distribution, hospitalization rates, and relapse frequency were similar between the phenotypes. C-reactive protein and ESR levels were significantly higher in the cutaneous-articular phenotype (P < .001), whereas hematological indices and complement levels did not differ significantly between groups. The ANA positivity was approximately 3-fold more frequent in children with articular involvement (27.3% vs. 8.8%, P < .001); however, the frequency of rheumatologic disease development during follow-up was similar between phenotypes (P=.42). Receiver-operating characteristic analyses demonstrated modest discrimination with low specificities for CRP and ESR. CONCLUSION: Children with cutaneous-articular IgAV show a higher inflammatory profile than those with skin-limited disease. However, routine laboratory markers have limited utility for phenotypic discrimination. Despite higher ANA positivity in the cutaneous-articular phenotype, similar rates of additional rheumatologic diagnoses during follow-up suggest that this finding should be interpreted cautiously.