Langerhans cell histiocytosis can have focal or systemic changes, with an acute or slow onset and a duration as short as a few weeks or as long as several years, with relatively specific clinical manifestations for each subtype, but transitional or overlapping manifestations can occur. The degree of clinical involvement varies among patients of different ages. The younger the age of onset, the greater the number of organs involved, and the more severe the disease. I. Typical symptoms 1. Skeletal lesions: (1) seen in almost all patients with Langerhans cell histiocytosis, with single or multiple lesions. The main manifestation is osteolytic damage, which can be completely repaired without leaving traces. (2) The lesions are locally swollen and painful, usually without redness or fever, and fractures may occur after minor trauma. Cranial lesions are most common, and other long and flat bones and pelvis are also frequently involved. The skull damage is initially a mass, hard, gradually becoming soft, with a sense of fluctuation, and then forming a defect, clearly demarcated from normal bone. (3) Damage to the jaw bone may cause swelling of the gums and loosening or loss of teeth. Invasion of mastoid and middle ear may result in ear drainage and infection. Involvement of posterior bulbous tissue may cause proptosis.2. Rash: Common in infants less than 1 year old. It is mostly distributed on the trunk, head and neck, and less frequently on the extremities. Initially, it is a red or brownish-yellow maculopapular rash, followed by a hemorrhagic, eczema-like or seborrheic rash, followed by crusting and desquamation, leaving white spots or hyperpigmentation. The rash often occurs in batches, and all phases of the rash may coexist. 3. Liver, spleen and lymph nodes are enlarged: liver involvement is often associated with abnormal liver function, jaundice, hypoproteinemia, prolonged prothrombin time, etc. In severe cases, liver failure may occur. As the rash subsides, the enlarged liver, spleen and lymph nodes may shrink.4. Pulmonary infiltration: symptoms vary in severity, often manifesting as cough, shortness of breath, and in severe cases, dyspnea and even respiratory failure. It can be complicated by pulmonary blisters, pneumothorax, emphysema, etc. Often combined with recurrent respiratory infections. Other symptoms of lymph node lesions: Langerhans cell histiocytosis lymph node lesions can take three forms. 1. simple lymph node lesions, i.e. primary eosinophilic granuloma of lymph nodes. 2. concomitant lesions of limited Langerhans cell histiocytosis, often accompanied by osteolytic lesions or skin lesions. 3. part of generalized diffuse lesions. It often involves isolated lymph nodes in the neck or inguinal region and may have localized pain. The prognosis is good for those with simple lymph node involvement.