"Primary" pulmonary Langerhans cell histiocytosis in a two-year-old child: case report and literature review.

Langerhans cell histiocytosis (LCH) can involve multiple organs. "Primary" or isolated pulmonary LCH is a well-described entity in young adults but is exceedingly rare in children younger than 15 years of age. The authors report a new case in a 2-year-old girl and review other reported cases in the pediatric population. The patient had had respiratory symptoms since early infancy suggestive of hyperactive airway disease. At 2 years of age, she had severe pulmonary insufficiency with remarkable cystic changes noted on chest imaging studies. Biopsy of a pulmonary lesion confirmed the diagnosis of LCH. She had no other organ involvement. Pulmonary histiocytosis, though rare, should be considered in any child with chronic respiratory disease such as bronchial asthma, especially when the response to anti-asthma treatment is poor and/or there are cystic changes on the chest x-ray.