Immunohistologic findings and adhesion molecule pattern in primary pure cutaneous Rosai-Dorfman disease with xanthomatous features.

Skin involvement is common in sinus histiocytosis with massive lymphadenopathy (SH, Rosai-Dorfman disease), but pure cutaneous cases are rare. A 70-year-old woman presented with a 10-year history of large red-orange nodules and plaques on her upper arms, face, and buttocks, without evidence of lymphadenopathy or internal involvement. Distinctive histopathologic differences were observed according to the duration of the lesions. In recent lesions, the dermal infiltrate was mostly composed of sheets of characteristic SH cells; on the other hand, in long-lasting lesions, the presence of xanthomatous changes and prominent fibrosis, in keeping with the self-limited nature of this disease, raises problems of differential diagnosis with other xanthohistiocytic disorders. Immunophenotypic studies showed that the SH cells are S-100+ CD1a negative-activated macrophages, capable of lysosomal activity. The adhesion molecule pattern of SH cells (CD11b+, CD11c+, CD18+, CD62L+, and CD103+) was similar to that of circulating monocytes, suggesting their recent migration from the bloodstream.