For children with unexplained fevers, painful mouth sores, and gut inflammation that resemble Behçet's disease (BD) but do not meet diagnostic criteria, clinicians have long faced a diagnostic challenge. Now, researchers from Peking Union Medical College Hospital have published a review in the World Journal of Pediatrics that formalizes the concept of Behçet's spectrum disorders (BSD), a framework first introduced in 2020 that unites a range of inflammatory conditions—from rare monogenic diseases to common recurrent canker sores—through shared immune pathways. The framework aims to help clinicians recognize Behçet-like inflammation earlier and prioritize genetic testing in children whose symptoms fall outside classic diagnostic patterns.
Behçet's disease is a systemic vasculitis characterized by recurrent oral and genital ulcers, but pediatric presentations are often partial or atypical, complicating diagnosis. Moreover, a growing number of monogenic autoinflammatory disorders produce nearly identical mucocutaneous and gastrointestinal symptoms yet are biologically distinct and require different therapeutic approaches. This overlap frequently leads to misdiagnosis, inappropriate treatment, and prolonged suffering. Although the BSD concept was introduced in 2020 to link these conditions through shared inflammatory pathways, a practical, clinically applicable framework for early recognition and genetic prioritization in children has remained elusive.
The review proposes a tiered classification: "core BSD" for monogenic diseases that converge on Behçet's-defining inflammatory pathways, and "peripheral BSD" for conditions with partial clinical overlap or indirect mechanistic connections. Core BSD includes monogenic diseases that disrupt NF-κB or JAK-STAT signaling—specifically HA20 (caused by TNFAIP3 mutations), RELA haploinsufficiency, NFKB1 haploinsufficiency, and ELF4 deficiency. These consistently feature recurrent mucocutaneous ulceration and strong convergence on BD-relevant inflammatory circuits. Peripheral BSD includes polygenic or multifactorial entities such as recurrent aphthous stomatitis (RAS), PFAPA syndrome, DADA2, and trisomy 8-associated disease, which exhibit partial clinical overlap but lack a defining monogenic driver. The authors identify NF-κB and JAK-STAT as two central inflammatory hubs common across the spectrum and delineate exclusion criteria to distinguish true spectrum members from phenotypic mimics like LIG4 deficiency and IKBKG (NEMO) mutations.
Clinically, the BSD framework enables earlier recognition of Behçet-like phenotypes and guides rational genetic testing, allowing targeted therapies—such as IL-1, TNF, or JAK inhibitors—for specific subsets. It also helps exclude non-spectrum mimics, avoiding unnecessary investigations and expediting effective care. Scientifically, it unifies disparate inflammatory disorders under shared pathogenic axes, fostering collaborative research and paving the way for biomarker discovery and mechanism-based trials. The framework is especially valuable in early-onset or atypical cases, where genetic testing can distinguish between conditions that look alike but respond to very different treatments. As the authors noted, "If a child shows up with recurrent mouth ulcers, fever, and gut inflammation that doesn't quite fit Behçet's criteria, the BSD framework gives us a roadmap for what to test for and why."
The full review is available at https://doi.org/10.1007/s12519-026-01035-4.
