ALK and sinus histiocytosis with massive lymphadenopathy: Within the xanthogranuloma family, it has a spectrum of histopathological features and is characterized by the infiltration of tissues by foamy CD68, factor XIIIa, and negative for CD1a and CD207 (langerin) histoiocytes.7 Rosai-Dorfman disease (RDD), Along with juvenile xanthogranuloma (JXG), ALK-positive histiocytosis (APH), and histiocytic sarcoma (HS), it belongs to the histiocytic neoplasms in the The 5th edition of the World Health Organization (WHO) Classification of Haematolymphoid Tumours.8