Cutaneous Rosai-Dorfman Disease Mimicking Granulomatous Dermatoses: A Rare Case Report.

Cutaneous Rosai-Dorfman disease (CRDD) is a rare non-Langerhans cell histiocytosis that mimics various granulomatous and neoplastic dermatoses, often leading to misdiagnosis. We report an 18-year-old male with a 13-year history of progressively enlarging erythematous plaques over the nasal bridge and right forearm, initially diagnosed as granulomatous inflammation. Histopathological examination revealed emperipolesis only after meticulous serial sectioning, and immunohistochemistry confirmed the diagnosis of CRDD. This case underscores the diagnostic challenges of CRDD, particularly in regions endemic for tuberculosis and leprosy, and highlights the importance of thorough histopathological and immunohistochemical evaluation in differentiating it from other dermatoses.