Dapsone as a potential treatment for cutaneous Rosai-Dorfman disease with neutrophilic predominance.

A 31-year-old Taiwanese woman, who from her medical history was generally well, presented with 1 slowly enlarging elevated plaque on the posterior aspect of her right shoulder. This had first been detected 3 months before the visit to our clinic. The lesion had originated as a small, tender, erythematous papule and had since grown into a large confluent plaque with satellite papules. She claimed that the lesion was increasing in size, and this was accompanied by intense itching and fever. On physical examination, there was 1 palm-sized, dusky red, elastic firm plaque on the right shoulder. The main lesion was surrounded by multiple 2to 8-mm erythematous satellite papules (Figure 1). There were no palpable cervical, supraclavicular, axillary, or inguinal lymph nodes. A systemic workup that included head, neck, and chest computed tomographic scans showed no involvement of other organs. Workups done to determine the source of her febrile episodes yielded no evidence of active infection. The only abnormal laboratory finding was polyclonal hypergammaglobulinemia found on serum protein electrophoresis. An incisional biopsy was performed. Microscopically, a dense dermal infiltrate extended from the upper dermis deep to the subcutis (Figure 2). The infiltrating cells were mainly composed of histiocytes with large vesicular nuclei. They also had abundant cytoplasm with spidery borders. Neutrophils, lymphocytes, and plasma cells were scattered between the histiocytes, and the presence of lymphocytes engulfed within the histiocytic cytoplasm, a feature called emperipolesis, was also noted. The mixed infiltration was neutrophil predominant. Immunohistochemical studies revealed histiocytes that stained positively for S100 protein and CD-68. Notably, the dermis surrounding the histiocytes was infiltrated by numerous neutrophils. Clinically and histologically, she was diagnosed as having cutaneous Rosai-Dorfman disease (CRD). Before visiting our hospital, she had been treated at a dermatologic clinic for 2 months, first with topical triamcinolone, oral prednisolone (30 mg/d), and then with oral isotretinoin (100 mg/d). However, the lesion had continued to worsen and the symptoms of pruritus and intermittent episodes of fever had progressed during the treatments. Superficial irradiation was suggested, but the patient refused owing to its potential hazards.