Rosai-Dorfman disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is a benign self-limiting disorder of unknown aetiology, which is frequently mistaken for lymphoma. There is no consensus as to the proper management of this disorder. In the past, potentially harmful treatments, such as antineoplastic drugs, have been advocated. We describe a 25-year-old woman with RDD who has had a remarkably favourable response to oral prednisolone therapy. Our observation strengthens the conclusions of previous case reports as to the effectiveness of corticosteroids in this condition. This article is aimed at creating awareness among clinical oncologists about this pseudolymphomatous disorder and emphasizing the therapeutic role of corticosteroids.