Unsuspected Langerhans cell histiocytosis can be easily missed in a colonic biopsy.

Langerhans cell histiocytosis (LCH) involvement of the gastrointestinal tract (GIT) is rare. The infiltrate in a colonic biopsy can be dissimilar to classic cytomorphologic features. It could be patchy, restricted to the subepithelial lamina propria and the lesional cells might have prominent nucleoli with lymphocytes-dominant background. The GIT manifestations could be confused with infectious, allergic, immunodeficiency and inflammatory bowel diseases. The rarity of GIT lesions, unawareness of some atypical endoscopic and histologic features might lead to false negative results. We report a case of LCH in an 11-month-old baby that was clinically unsuspected and histologically overlooked.