A Case of Adult-Onset TNF Receptor-Associated Periodic Syndrome (TRAPS) with Somatic Mosaicism Treated with an IL-1 Inhibitor.

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) is a rare autoinflammatory disorder, and adult-onset cases caused by somatic mosaic TNFRSF1A variants are exceptionally rare. A man in his 60s developed recurrent febrile episodes with rash and polyarthralgia and was initially misdiagnosed with a biliary infection and adult-onset Still's disease. Hybrid capture-based next-generation sequencing identified a somatic mosaic TNFRSF1A variant with a variant allele frequency of 19%, thus establishing the diagnosis of TRAPS. Treatment with canakinumab resulted in complete clinical remission and successful glucocorticoid tapering.