Rosai–Dorfman disease presenting as choroidal melanoma: a case report and review of the literature

Background Rosai–Dorfman disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is a rare non-malignant proliferation of histiocytes of unknown aetiology. It was first recognised as a distinct clinicopathologic entity in 1969, and is classified as an idiopathic non-Langerhans cell histiocytosis. The disease process is usually self-limiting and often involves lymph nodes, but extranodal involvement is well-described and any anatomic site can be involved.