A 53-year-old male presented with dropping of the right eyelid associated with decreased visual acuity for 4 months. He also complained of vertical diplopia especially when looking down. Ophthalmological examination revealed right blepharospasm associated with right hypertropia. There was palpable mass at the inferomedial aspect of the right eye. Magnetic resonance imaging revealed abnormal signal intensity in the right orbit inferior aspect occupying the orbital floor and measured 2.7 cm × 2.5 cm × 1.2 cm and showed enhancement on the postcontrast study. The patient underwent complete excision of the tumor. Histological examination of the mass revealed histiocytic proliferation with emperipolesis, with positive S100, positive CD68, and negative CD1a staining. These histological and immunohistochemical features are consistent with extranodal Rosai-Dorfman disease. There was no complication or recurrence after the complete excision.
Keywords: Emperipolesis; Rosai–Dorfman disease; orbital; sinus histiocytosis with massive lymphadenopathy.