Case Report: Systematic endoscopic characterization of synchronous esophageal, gastric, and colorectal involvement in multisystem Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a rare neoplastic disorder derived from dendritic cells, predominantly affecting pediatric populations. Adult-onset LCH involving the gastrointestinal (GI) tract is exceedingly rare, with limited endoscopic descriptions. We describe a 34-year-old male with gingival swelling and mandibular osteolysis, ultimately diagnosed with multisystem LCH. Imaging revealed pulmonary nodules and diffuse gastrointestinal involvement, confirmed through high-resolution endoscopy. Characteristic findings included barnacle-like esophageal plaques, ulcerated gastric nodules, and clustered subepithelial masses in the colon. A novel 'mucosal fragmentation sign' was identified during resection-abrupt mucosal detachment revealing white, fish-flesh-like tumor tissue. Histology confirmed LCH with CD1a, S100, and langerin (CD207) positivity, alongside detection of a BRAF V600E mutation. This case is the first to systematically characterize concurrent esophageal, gastric, and colonic LCH involvement in an adult. Distinctive endoscopic patterns may support early diagnosis and optimized biopsy strategies in atypical clinical scenarios.