Crush cytology of Rosai-Dorfman disease of the central nervous system - A report of 2 cases

BACKGROUND: Rosai-Dorfman disease (RDD) of the central nervous system (CNS) is rare. There is no previous report on intraoperative crush cytology of this disorder. CASES: A 70-year-old man presented with headache and was found to have 2 intracranial extraaxial masses. A 62-year-old man presented with cauda equina syndrome secondary to a mass lesion in the sacral canal. The crush smears, prepared intraoperatively from a small portion of the biopsy specimen in each case, showed scattered lymphoid aggregates in a lighter background with a loose admixture of lymphocytes, plasma cells, usual histiocytes and RDD histiocytes. The RDD histiocytes contained single but sometimes multiple nuclei that were larger and more hyperchromatic than those of the usual histiocytes. Many RDD histiocytes had voluminous, pale pink cytoplasm. Lymphophagocytosis by RDD histiocytes was observed. The findings in the crush smears reflected the histology of the lesions. The lymphophagocytosis and nuclear details in the RDD histiocytes were more visible in the crush smears than in the frozen sections. CONCLUSION. Crush cytology appears useful, alone or in conjunction with frozen sections, in the intraoperative diagnosis of CNS RDD.