Cutaneous Rosai-Dorfman Disease presenting as a flank swelling

Rosai-Dorfman disease (RDD) is primarily a disease of lymph nodes caused by accumulation of excessive histiocytes. The extra-nodal sites are simultaneously involved in almost half the cases. However, presentation with isolated extra-nodal sites is uncommon and disease confined to skin and soft tissues is a rare entity. We report RDD in a 33 year old man who presented as a flank mass and was a diagnostic challenge for the surgical team. This case report strengthens the evidence that RDD should be added to the list of rare causes of skin and soft tissue swellings and informs how to manage such patients.