Cutaneous Rosai-Dorfman Disease Located on the Breast: Rapid Effectiveness of Methotrexate After Failure of Topical Corticosteroids, Acitretin and Thalidomide.

An erythematous cutaneous plaque on the breast with no signs of infection requires a skin biopsy to rule out dermal extension of an underlying mammary adenocarcinoma, primary skin tumour (e.g. angiosarcoma or malignant lymphoma) (1), or inflammatory lymphoedema of the breast (2). It can more rarely reveal location on the skin of systemic disease. Rosai-Dorfman disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is a benign proliferative disorder of histiocytes first described in 1965 by Destombes on nodal biopsy (3). It was subsequently recognised as a distinct clinicopathologic entity by Rosai & Dorfman (4). Cases of RDD located solely on the skin have rarely been reported, and thus treatment is not well-codified (5). We report a case of RDD on the breast which showed rapid partial response to methotrexate.