AbstractGastrointestinal tract involvement in Langerhans cell histiocytosis (LCH) is extremely rare, with limited documentation of endoscopic manifestations. We report a 19‐month‐old girl who presented with repeated diarrhea and bloody stools, accompanied by recurrent pulmonary infections, anemia, hypoproteinemia, thrombocytopenia, coagulopathy, and hepatosplenomegaly with lymphadenopathy. Initial treatment with antibacterial agents, mesalazine, thalidomide, and prednisone led to temporary improvement; however, the symptoms repeatedly relapsed. She underwent three digestive endoscopies, but until the third endoscopy, a definitive diagnosis of Langerhans cell histiocytosis was established through biopsy. While upper gastrointestinal tract findings were not significant, notable changes were observed in the colorectal region. A colonoscopy revealed progression from erythema to diffuse hyperemia and edema, with erythema, erosion, and superficial ulcers extending into the distal ileal mucosa. Genetic analysis identified a BRAF‐V600E mutation. Following treatment with chemotherapy (vincristine and prednisone) and the BRAF inhibitor dabrafenib, the patient demonstrated significant clinical improvement within days. At the 1‐year follow‐up, the patient had normal bowel movements and a weight gain of 2.5 kg. Early gastrointestinal endoscopy with multiple biopsies in suspected children can facilitate early detection. Dabrafenib is a viable treatment option for Langerhans cell histiocytosis.
