[Cutaneous revelation of Rosai-Dorfman disease: 7 cases].

BACKGROUND: Rosai-Dorfman disease (RDD) is a benign form of non-Langerhans-cell histiocytosis. It is identified by a particular histological profile first observed in febrile lymph nodes. Extranodal sites are frequent. The most common site is the skin, which can reveal the disease despite a difficult and delayed diagnosis. Seven cases of cutaneous revelation of RDD were studied retrospectively in order to delineate the clinical characteristics and facilitate diagnosis and treatment of this extremely rare disease. PATIENTS AND METHODS: Six cases of RDD from 1990 to 2011 were identified in the photographic and histopathological records of the Saint-Louis Hospital and one case came from a Bichat Hospital consultation. The diagnosis was based in all cases on histopathology results.
RESULTS: Patients consisted of four men and three women aged between 31 and 69 years. Cutaneous lesions (3 to 20) revealed the disease in all of them and the time from disease onset to diagnosis ranged from six months to five years. The clinical presentation was erythematous or orange popular nodules or plaques, usually on the face. Microscopically, a dense dermal infiltration was observed, in some cases extending into the subcutaneous tissue, with pale histiocytic cells characterised by emperipolesis, plasma cells, lymphocytes, some neutrophils and variable fibrosis. The diagnosis, initially erroneous in 4 cases, was rectified by a second reading of histopathology slides, and immunohistochemical studies showed expression of S-100 protein in histiocytes but not CD1a. Three patients had pure cutaneous RDD. Two neurological sites and one nasal site were also found, with one ENT site and sequelae of previous uveitis in one patient. All extra-cutaneous sites were identified by clinical examination. Different treatments were proposed according to the sites and impact of the disease. In one case, the lesions regressed spontaneously after 18 months. COMMENTS: Few RDD series have been published and they mainly concern Asian patients. The ethnic origin of our patients was varied. The main findings were: 1) common clinical findings (orange or erythematous papules or nodules, mostly on the upper body), which should alert the dermatologist and histopathologist to the possible diagnosis of RRD; 2) the possibility, already mentioned in the literature, of spontaneous regression and a good prognosis; 3) the need for thorough evaluation by thoracic, abdominal and cerebral CT (computed tomography) or more a PET (positron emission tomography) scan to screen for potentially dangerous visceral sites, and also clinical follow up.