Langerhans cell histiocytosis masquerading as acute appendicitis: Case report and review.

Langerhans cell histiocytosis (LCH) is a rare syndrome characterized by unifocal, multifocal unisystem, or disseminated/multi-system disease that commonly involves the bone, skin, lymph nodes, pituitary, or sometimes lung (almost exclusively in smokers) causing a variety of symptoms from rashes and bone lesions to diabetes insipidus or pulmonary infiltrates. We present a previously unreported case of gastrointestinal LCH as well as a novel characteristic lesion affecting the colon of a young woman who presented with signs and symptoms mimicking acute on chronic appendicitis. Immunohistochemical analysis of appendectomy specimen and nodular specimens on colonoscopy demonstrated S-100, CD1a, and langerin reactivity. The patient underwent systemic chemotherapy with cytarabine and demonstrated excellent response to therapy.