[Purely cutaneous Rosai-Dorfman disease present for 19 years]

Rosai-Dorfman disease is a non-Langerhans histiocytosis chiefly affecting lymph nodes sites. In rare cases, it presents in the form of isolated skin lesions, without adenopathy, in which case it is a benign disease that regresses spontaneously within our number of months and years.

An 83 year-old man presented with multiple red-brown nodular lesions on the upper part of the body that had been progressing over a period of 19 years. Histological examination showed infiltrate characteristic of Rosai-Dorfman disease, with numerous dermal foci of histiocytes expressing protein S100 but not expressing CD1a on immunohistochemical analysis, as well as emperipolesis. The lymph nodes sites were unaffected, and the remainder of the clinical and laboratory examinations were normal, indicating a purely cutaneous form of the disease. Treatment with isotretinoin was ineffective and the lesions continued to spread gradually, being treated from time to time with CO2 laser or cryotherapy.

Our case is atypical in terms of clinical presentation since it involved diffuse nodular lesions. The disease course was also unusual in that no spontaneous regression was observed even after 19 years.