Pulmonary Langerhans Cell Histiocytosis

Langerhans cell histiocytosis is a rare idiopathic disorder, characterized by the infiltration of 1 or more organs by large mononuclear cells. It can develop at any age. Pulmonary Langerhans cell histiocytosis (PLCH) is found more frequently and is better described in adults than in children. The PLCH findings on computed tomography (CT) scans include nodular opacities, thin-walled cysts (often bizarre in shape), and marked parenchymal fibrosis. The purpose of this study was to compare the chest CT findings between adults and children with PLCH.We retrospectively analyzed the chest CT findings in a series of 7 children and 12 adults. Two independent observers reviewed the CT studies of all cases, and then correlated their observations. Statistical analysis was done with the Fisher exact test.The mean ages were 8 years (3 mo to 16 y) for the pediatric group and 39 years (21 to 59 y) for the adults. Extrapulmonary disease was present in 3 (43%) children and 1 (8.3%) adult. All the adults reported smoking, and only 1 pediatric patient (16 y old) had a history of smoking. The CT findings were characterized by the presence of cysts, fibrosis, and nodules, with the findings being similar in size and appearance for both populations. However, the distribution was different; the subpleural parenchyma in the costophrenic recess was spared in the entire adult group, but not spared in any of the pediatric patients.The CT findings of PLCH were similar in the adult and the pediatric populations, with the exception that costophrenic recess subpleural parenchyma was spared in the adult group but demonstrated pathology in the pediatric group.