PRKCD and juvenile idiopathic arthritis: Due to the atypical onset of diffuse lymphadenopathy in a child with polyarticular JIA, a next generation sequencing panel of genes associated with autoimmune lymphoproliferative syndrome was performed, revealing the heterozygous c.742G>A, p.Gly248Ser missense mutation of PRKCD, later confirmed by Sanger sequencing.