Ultrasound's role in differentiating camptodactyly-arthropathy-coxa vara-pericarditis (CACP) syndrome from inflammatory arthritis in children. A narrative review.

Camptodactyly-arthropathy-coxa vara-pericarditis (CACP) syndrome is a rare genetic disorder characterized by a combination of congenital flexion contractures of the fingers (camptodactyly), non-inflammatory joint swelling (arthropathy), hip deformities (coxa vara), and recurrent pericarditis. In early childhood, the clinical presentation is dominated by the articular manifestations that can easily mimic juvenile idiopathic arthritis, often leading to delayed diagnosis and inappropriate treatments. Although not pathognomonic, ultrasound may provide specific ultrasound characteristics of joint involvement in CACP syndrome that help differentiate it from inflammatory arthropathies. This report aims to highlight the role of ultrasound in the initial assessment, differential diagnosis, and ongoing monitoring of CACP syndrome, drawing on both our patient series and a review of the literature.