Cytological diagnosis of Rosai–Dorfman disease: A study of twelve cases with emphasis on diagnostic challenges

Rosai-Dorfman disease, also known as Sinus histiocytosis with massive lymphadenopathy, is a benign proliferative disorder of histiocytes. It typically affects lymph nodes; however, extranodal disease is being increasingly reported. The latter entity poses exceptional diagnostic challenge clinico-radiologically by forming mass lesions. Fine needle aspiration cytology (FNAC) is the investigation of choice to avoid unnecessary surgery as the majority are self-limiting.