Rectal extranodal Rosai-Dorfman disease diagnosed by EUS-FNA: a case report and review of the literature.

Rosai-Dorfman disease (RDD), also known as "sinus histiocytosis with massive lymphadenopathy," only rarely involves the gastrointestinal (GI) tract. Therefore, this unusual site of presentation can be challenging for the pathologist. We present a case of RDD manifesting as a rectal submucosal mass associated with rectal bleeding in a 54 year old woman. The diagnosis was made on cytologic preparations obtained through endoscopic ultrasound guided fine needle aspiration (EUS-FNA) and subsequently confirmed by biopsy. To our knowledge, this is the first time extranodal RDD of the GI tract has been diagnosed by EUS-FNA. A review of previously published cases of GI RDD is presented to increase awareness of this exceptional presentation.