Neonatal urticaria: Could it be CAPS?

A neonatal boy presented with a persistent urticarial rash. Initial investigations showed raised inflammatory markers and evidence of systemic inflammation. A working diagnosis of cryopyrin-associated periodic syndrome (CAPS) was made, and the patient responded extremely well to Anakinra. Molecular genetic testing revealed a somatic mutation (affecting 12.5% of cells) in the NLRP3 gene, accounting for the persistent inflammatory state but milder phenotype as seen in our patient.