In recent years, studies of RDD using next-generation sequencing found neoplastic conditions, point mutations occur in 33–50% of RDD cases, affecting KRAS, NRAS, SMAD4, ARAF, or MAP2K1, which is not found in IgG4-RD [23–25]. Here, SMAD4 is linked to sinus histiocytosis with massive lymphadenopathy.