Imaging Study In Pediatric Langerhans Cell Histocytosis

Objective: To investigate the distributional characteristics and imaging features in pediatric Langerhans cell histocytosis.Methods:1.117 patients who were under 18 years old were collected from January 2012 to December 2017,which were histologically diagnosed with Langerhas cell histocytosis.They underwent CT(n=39)or MRI(n=23),or CT and MRI(n=55).According to lesion locations,all patients were divided into four groups: Group I~IV.We analyzed the distributional characteristics and imaging features of each system,including site,morphology,size,distribution,density and singal intensity.2.36 padiatric patients were collected from January 2006 to December 2012.All patients were divided into three groups(Group V~VII)based on the involvement of liver and lung.Among them,30 underwent CT,1 underwent MRI and the rest patients underwent both CT and MRI.Besides,all hepatic LCH underwent abdominal enhanced examination.Then we analyzed the morphology,size,distribution,density and singal intensity of the lesion.Results:1.There were 70 boys and 47 girls in a total analyze of 117 patients with sex ratio of 1.5:1.0 and age range from 4 month to 12 years old,the peak year was from 1years old to 3 years old.The differences between the four groups were significantly important.Moreover,the age of MS-LCH patients were much younger than that of SS-LCH.The most common part was the skeletal system(94%),followed by liver(15%),spleen(11%),lung(9%),skin(9%),pituitary(7%)and lymphoid(1%).2.The common radiographic manifestation of skeletal LCH includes osteolytic destruction and soft tissue mass.The lytic destruction of different bone has different shapes,which were Punched-out lesion,beveled edge sign and geographic sign in skull,vertebra plana in spine,lytic lesion with periosteal reaction in long bones,expansive osteolytic lesion with sclerotic rim in flat bones.3.When LCH involves pituitary,we can see absent posterior pituitary spot on T1 W MR images as well as thickening and ehancement of pituitary stalk.The mean anteroposterior diameter of pituitary stalk is 3.6 mm,while the mean left to right diameter of pituitary stalk is 4.2mm.4.Both pediatric hepatic LCH and PLCH were MS-LCH.On the basis of distribution,the imaging features of pediatric hepatic LCH can be divided into central type(19/29,66%),which shows lesions distributed along the portal vein trees;peripheral type(2/29,7%),which shows lesions located in the peripheral regions of the liver;and mixed type(8/29,27%),which combining the above two lesions.Other signs include hepatomegaly(21/29,73%),splenomegaly(21/29,73%)and dilatation of intrahepatic bile ducts(21/29,73%)).The principal manifestation of PLCH was the presence of different sized nodular-like lesions(50%)and cystic-like lesions(83%),which distributed along the bronchiolar axis.While the nodular-like lesions usually located in the upper lobes of lung,cystic-like lesions more often located in the distal of the small airways.Both these two lesions can involve costophrenic angle.Conclusions:1.Though LCH is strongly heterogeneous and can involve different systems and organs,we can still diagnose the disease by combining the typical radiographic manifestations and clinical features.2.There have a lot in common in radiographic distribution and morphology between pediatric hepatic LCH and PLCH,and these radiographic features can help us diagnose LCH qualitatively.