Cutaneous Rosai-Dorfman disease presenting as a granulomatous rosacea-like rashs

A case of cutaneous Rosai-Dorfman disease (CRDD) presenting as a granulomatous rosacea-like rashs was reported. A 45-year-old Chinese woman presented with a 1-month history of a widespread nonpruiginous papulonodular eruption. The rash had begun on her face and rapidly progressed to involve the neck and extremities. She was otherwise healthy, with no history of fever, malaise, or weight loss. Physical examination revealed multiple symmetrically distributed discrete and coalescing red plaques, papules and nodules scattered over the face, neck and extremities. No appreciable lymphadenopathy or hepatosplenomegaly was noted. There was no mucosal involvement. The biopsy specimen obtained from the face demonstrated the epidermis was normal, while the superficial dermis contained sheets of histiocytes with abundant, focally foamy cytoplasm. The histiocytes were surrounded by a patchy lymphocytic and plasma cell infiltrate. There was no significant histiocytic atypia. Some of these histiocytes engulfed, without destroying, lymphocytes and neutrophils (emperipolesis). Immunohistochemical staining revealed that the histiocytes were strongly positive for S100 protein, weakly positive for CD68, and negative for CD1a. A diagnosis of CRDD was made. Oral prednisone therapy was initiated at a dosage of 30 mg/d for 3 weeks and then tapered over the ensuing 2 weeks. After 5 weeks of treatment, the lesions had markedly improved.