Orbital masses as a rare presentation of Rosai-Dorfman disease: Clinicopathologic characterization of five cases.

Rosai-Dorfman disease (RDD) is a rare, non-Langerhans cell histiocytosis. Most cases present with marked, non-tender lymphadenopathy due to the proliferation of atypical histiocytes. A minority of cases involves extranodal sites and can present as bone lesions, skin rashes, pulmonary nodules, and rarely orbital masses. Orbital involvement in RDD is rare and may infrequently present as an isolated tumor mass without lymphadenopathy. This study aims to better characterize this uncommon presentation of this rare disease. Five cases of orbital RDD were identified from the last 18 years and the clinical characteristics of each case were compared with histopathological findings. Three men and two women ages 12-36 presented with complaints of eye swelling and/or vision changes. One patient had a history of neurofibromatosis type I and inflammatory pseudotumors while the other four had no signs of systemic disease or other sites of extranodal involvement at the time of presentation. Masses ranged in size from 1.0 cm to 3.5 cm and primarily involved the superior orbit. Resected lesions all displayed characteristic findings of admixed atypical histiocytes, lymphocytes, and plasma cells with a fibrotic background. Emperipolesis was seen in all cases. Immunostaining for S100 and CD68 was diffusely positive in the histiocyte population. Clinical follow-up was obtained for 4 of 5 patients: all four were disease-free at 1 to 15 years after resection. RDD should be considered in the differential for patients with orbital masses, even in the absence of lymphadenopathy or signs of systemic disease.