Cutaneous Rosai-Dorfman Disease: A Case Report.

Rosai-Dorfman disease (RDD) is a rare benign non-Langerhans cell histiocytosis. The most common site of extranodal involvement is the skin. Cutaneous involvement without lymphadenopathy is extremely rare. It is often difficult to diagnose primary cutaneous RDD secondary to the non-specific nature of its clinical and histologic features. Consequently, diagnosis can be significantly delayed. To our knowledge, about 220 reports of purely cutaneous RDD are documented in the literature to date. We present an additional unique case of cutaneous RDD and emphasize the challenging nature of accurate clinical and histopathologic diagnosis.