Abstract

Context: Rosai-Dorfman disease is an uncommon histiocytic disorder most frequently presenting as bilateral cervical lymphadenopathy in children and young adults. The extranodal disease occurs in a significant proportion of patients. Although cutaneous disease without lymphadenopathy is very rare, it has been documented. Compared with patients with systemic Rosai-Dorfman disease, patients with primary cutaneous Rosai-Dorfman disease are older, women are more commonly affected, and whites are more likely than blacks to be afflicted. We present an unusual case of Rosai-Dorfman disease with only cutaneous manifestations. Design: A 56-year-old woman presented with multiple skin nodules on bilateral arms that gradually increased in size over 6 months with occasional pain and pruritus. The patient had no previous medical history. The lesion is biopsied. Results: The H&E section demonstrates a dermal infiltration composed predominantly of epithelioid histiocytes with enlarged, round to oval hypochromatic nuclei and abundant eosinophilic cytoplasm, and prominent emperipolesis in a background of lymphocytes and plasma cells. Associated sclerosis was noted. The histiocytes in RDD are positive forS100, and CD68 (Figures C and D) and are negative for CD1a and langerin (CD207), thereby excluding Langerhans cell histiocytosis (CD1a+ langerin+). Conclusion: Cutaneous Rosai-Dorfman disease is very rare with clinical variability of the lesions. The most important differential diagnosis is Langerhans cell histiocytosis and juvenile xanthogranuloma followed by reticulohistiocytoma, lymphoma, sarcoidosis, and infectious diseases, which should always rule out.

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