Rosai Dorfman disease (sinus histiocytosis with massive lymphadenopath
y (SHML)) is a benign self-limiting disorder that commonly involves th
e lymph nodes. We reviewed eight cases of this entity aiming to docume
nt the cytomorphological features. Of the eight cases, a preoperative
diagnosis was suggested in seven cases. Pertinent features included: n
umerous large histiocytes with prominent emperipolesis (documented by
a halo around the cell), fine vacuoles in the cytoplasm and lymphocyte
s and plasma cells in the background. In some cases the histiocytes sh
owed atypia. In one biopsy-proven case a diagnosis of Hodgkin's was su
ggested, emphasizing the pitfalls associated with the FNA diagnosis of
this lesion.