Manifestations and outcomes of digestive tract involvement in adult Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH) is a heterogeneous histiocytosis characterized by proliferation of Langerhans cells. While less common, manifestations of digestive tract involvement in LCH remain largely unrevealed. We conducted a retrospective analysis of demographics, clinical, endoscopic, genetic and follow-up data from 13 adult patients with pathologically confirmed gastrointestinal involvement of LCH (LCH-GI), in a single-center cohort of 465 patients. Digestive tract involvement was observed in 2.80% of LCH patients. At LCH-GI diagnosis, 7 patients (53.8%) had unifocal lesions, and 6 patients (46.2%) had multisystem disease. 6 patients (46.2%) experienced no gastrointestinal symptoms at LCH-GI onset, while others were symptomatic. Stomach was most commonly affected (61.5%), followed by esophagus (23.1%), colon (7.7%) and anus (7.7%). Endoscopic findings varied among 12 patients, including submucosal bulge (8 patients, 66.7%) and non-bulging lesions (4 patients, 33.3%) such as erosions, coarse granular mucosa, and regional abnormal coloration. Among 8 patients with genetic analysis, BRAF mutation was detected in 5 patients (62.5%). The estimated 1-year overall survival rate was 91.7%. Progression-free survival of patients with submucosal bulges under endoscopy was significantly better than those with non-bulging lesions. This study presents 13 cases of LCH with digestive tract involvement. We emphasize the importance of endoscopy and biopsy for pathological examination of lesions such as submucosal bulges and erosions under endoscopy to assist in early detection of LCH. Comprehensive systemic assessment and regular endoscopic monitoring are essential in patient management. Treatment should be individualized with dynamic adjustments during follow-up.