Rosai-Dorfman disease with primary cutaneous manifestations--a case report.

Rosai-Dorfman disease (sinus histiocytosis with massive lymphadenopathy) is a benign systemic proliferative disorder of histiocytes resembling the sinus histiocytes of lymph nodes. The typical clinical features of this disease include bilateral painless lymphadenopathy, fever, and polyclonal hyperglobulinaemia. The condition may present with extranodal involvement in 43% of cases, and cutaneous lesions are the most common form of extranodal diseases. However, purely cutaneous Rosai-Dorfman diseases occur rarely, particularly among Orientals. We describe a 48-year-old female presenting with an erythematous dermal nodule on the abdomen. Complete physical examinations and laboratory tests demonstrated that the lesion was only limited to the skin. Histologically, the lesion consisted of proliferative large histiocytes frequently exhibiting emperipolesis. Immunohistochemical and ultrastructural studies were also performed. The former showed characteristic cytoplasmic staining of histiocytes against S-100 protein. Because cutaneous Rosai-Dorfman disease may be unfamiliar to most pathologists, cases limited to the skin are probably underestimated.