The conundrum of juvenile spondyloarthritis classification: Many names for a single disease? Lesson learned from an instructive clinical case

Pediatric rheumatic diseases are often characterized by an evolving phenotype, resulting in diagnostic dilemma for physicians involved in their management. Although several classification criteria are used in childhood to uniform patients' diagnoses, several conditions share similar clinical features and therefore their classifications may overlap or be ambiguous. This is particularly paradigmatic for the classification of juvenile spondyloarthritis (JSpA), as the currently available criteria do not encompass their complexity. The differential diagnosis of sacroiliitis is often challenging for clinicians and requires considering several conditions, which include infective, neoplastic and rheumatic diseases. We report the case of a 13-year-old boy with an evolving clinical phenotype; its progression shows the wide differential diagnosis required in pediatric rheumatic diseases and emphasizes the issues of the actual classification system.