“…However, many authors also commented on the nuclear atypia of the RDD histiocytes, which included nuclear enlargement, nuclear hyperchromatism and nucleolar prominence when compared with the usual histiocytes. 21,24,27,28,30,32,35 CNS RDD is difficult for the pathologist to diagnose, especially during an intraoperative consultation, because it is very difficult to discern the atypical nuclear features and lymphophagocytosis of RDD histiocytes on frozen section slides. Recent progress in cytology has proven the usefulness of crush preparations in cytologic diagnosis, especially in the field of neuropathology.…”