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. Cutaneous RDD is often associated with infections, immunodeficiency, and autoimmune disorders. A 52‐year‐old patient presented with disseminated, recurrent, and relapsed pure cutaneous RDD that responded well to treatment with sirolimus and local infiltrations of methylprednisolone. The patient had multiple nonpainful nodular and tumour‐like lesions, histiocytic infiltrates with emperipolesis were observed on histologic examination, and positive immunohistochemistry for CD68, and S100. There is no standardised treatment, then the patient was treated with various therapies, including systemic steroids, chemotherapy (cyclophosphamide, doxorubicin, vincristine, and prednisone), radiotherapy, and other immunosuppressive treatments. Some lesions were treated surgically, resulting in recurrence. Sirolimus and local infiltration with methylprednisolone were tried as salvage treatments, the patient responded well, reducing the incidence of new lesions during follow‐up, and the size of the preexisting lesions.