Recalcitrant primary cutaneous Rosai-Dorfman disease. Efficacy of sirolimus and intralesional methylprednisolone.

Sinus histiocytosis or Rosai-Dorfman disease (RDD) is a rare disorder with severe lymphadenopathy and a limited clinical course, the aetiology of which is still controversial. The disease usually affects cervical nodes, with fever, polyclonal gammopathy, and leucocytosis with neutrophilia. Pure cutaneous involvement occurs as the only manifestation in only 3% of cases.