Primary Cutaneous Rosai-Dorfman Disease: A Cyto-Histo Correlate.

Primary cutaneous Rosai-Dorfman disease (RDD) is a rare proliferative disorder of histiocytes involving exclusively skin. The diagnosis of cutaneous RDD relies on clinical, histopathological and immunohistochemical findings. Cytological diagnosis can also be made in the presence of diagnostic features like histiocytic proliferation and prominent emperipolesis. We present two rare cases of primary cutaneous RDD: a 20-year-old male and an 8-year-old male, diagnosed on fine-needle aspiration cytology (FNAC). The first case was multicentric with swellings on the nose and arm, while the second patient had a single swelling on the right pinna. FNAC was reported as cutaneous RDD in both cases, which was later confirmed on histopathology and immunohistochemistry.