以前将朗格汉斯细胞组织细胞增生症（Langerhans cell histiocytosis，LCH）定义为朗格汉斯型组织细胞的增生，具有多样化的临床表现，主要发生在儿童。典型表现为逐渐增大、无痛的颅骨肿块。临床迅速恶化的情况很少发生。这里报道一个3岁男孩，因前右侧头部撞击受伤，未见明显神经功能缺陷。随后该区域多次出现瘀伤。初次受伤后的6天内，右额部肿胀逐渐增大。颅骨X线摄影未显示有骨病变。初次受伤后的12天，同一部位显著增大。磁共振成像显示前额骨肿瘤病灶与多发皮下囊肿病灶相关。病人接受颅骨病变的开放性活检和皮下病灶的清除术。组织病理学检查确诊为LCH。免疫组织化学评估显示CD1a和朗格纤维蛋白阳性，BRAF V600E阴性。活检后颅骨病灶在30天后自动消失，未复发。医生应该对这种通过重复头部损伤而发展起来的LCH罕见临床表现有所认识。

Langerhans cell histiocytosis (LCH) was previously characterized as the proliferation of Langerhans-type histiocytes with a wide range of clinical presentations that arise mostly in children. The typical presentation is a gradually enlarging, painless skull mass. Rapid clinical deterioration is rare.A 3-year-old boy who had incurred a right frontal impact head injury demonstrated no apparent neurological deficits. He subsequently bruised the same region multiple times. The right frontal swelling gradually increased over the course of 6 days after the initial injury. Skull radiography showed no bony lesion. The same site enlarged markedly 12 days after the initial injury. Magnetic resonance imaging revealed a frontal bony tumorous lesion associated with multiple subcutaneous cystic mass lesions. The patient underwent open biopsy of the skull lesion and evacuation of the subcutaneous lesions. Histopathological examination confirmed the diagnosis of LCH. Immunohistochemical evaluation revealed positivity for CD1a and langerin and no immunopositivity for BRAF V600E. The skull lesion spontaneously disappeared 30 days after the biopsy without recurrence.Physicians should be aware of this rare clinical manifestation of LCH that developed by a repeat head injury.