Adult Langerhans Cell Histiocytosis Presenting as an Isolated Rectal Polyp and Hematochezia.

Langerhans cell histiocytosis (LCH) is a rare disorder characterized by the abnormal proliferation and accumulation of Langerhans cells, which are specialized dendritic cells involved in antigen presentation. LCH most commonly involves the skin, bone, and lung. The gastrointestinal tract is an uncommon site of disease, and LCH presenting as a solitary colonic polyp is extremely rare. We present a case of a 53-year-old male with hematochezia who had a rectal polyp that was confirmed both histologically and immunohistochemically to be LCH. There was no evidence of systemic involvement of LCH.