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Special Feature
November 1999

Pathological Case of the Month

Arch Pediatr Adolesc Med. 1999;153(11):1199-1200. doi:

Figure 1. Severe exophthalmos.

Figure 2. Abnormal tissue completely occupying the orbital spaces, slightly infiltrating the anterior fossa up to the sella.

Figure 3. Orbital tissue. Left, Sheets of large, pale to eosinophilic polygonal histiocytic cells with large vesicular nuclei and small nucleoli; occasional multinucleated histiocytes and spindle-shaped histiocytes were also present (hematoxylin-eosin, original magnification ×150). Right, The histiocytic cells stained positive for S100 protein (alkaline phosphatase anti–alkaline phosphatase, original magnification ×150).

Rosai-Dorfman disease (RDD) is an uncommon proliferative disorder of histiocytes that was first described in 1969.1

Generally, RDD is characterized by massive lymphadenopathy (frequently accompanied by anemia), increased erythrocyte sedimentation rate, and elevated levels of serum immunoglobulins. Histologically, this condition is characterized by a proliferation of large pale cells that show striking lymphocytophagocytosis (emperipolesis) and immunoreactivity for S100 protein.2 However, it has only recently been described as a distinct entity in soft tissue, with pernicious locally recurrent lesions.3,4