OBJECTIVESTo observe the clinicopathologic features of Langerhans cell histiocytosis (LCH), and to evaluate the values of langerin, CD1a and S-100 protein expression in diagnosis of the tumor.

METHODSTotal 258 cases of Langerhans cell histiocytosis in the past 18 years (from 1992 to 2008) were collected, morphologic review and immunohistochemical staining were performed.

RESULTSIn all 258 cases, the ages of patients older than 16 years or younger than 2 years were 126 (48.8%) and 37 (14.3%), respectively, in the remaining 95 (36.8%) of the cases, the age of the patients ranged from 2 to 16 years. For all of 258 cases, there were 364 diseased sites. Bony lesions accounted for 77.2% (281 cases), especially the skull (112 cases, 39.9%), followed by lymph node (25 cases, 6.9%) and skin (14 cases, 3.8%). Clinically, unisystem or unifocal disease was predominant (201 cases, 77.9%), followed by unisystem and multifocal disease (21 cases, 8.1%), multi-system disease (26 cases, 10.1%), isolated pulmonary LCH (2 cases, 0.8%), and unclassified (8 cases, 3.1%). Histologically, variable number of Langerhans cells was present in 265 samples of 258 cases. Multinucleated giant cells were found in 166 (62.6%) of the samples. Eosinophils were the major infiltrating non-neoplastic cells, and eosinophilic abscess was seen in 57 cases (21.5%). Coagulative necrosis and dead bone were detected in 29 (10.9%) and 124 (46.8%) of the cases, respectively. Immunohistochemically, the expression of S-100 protein, CD1a and langerin was 99.1% (209/211), 100% (206/206) and 98.5% (193/196), respectively, and the sensitivity of them had no statistical difference.

CONCLUSIONSIn this group of LCH cases, the ratio of adult patients is high, but the proportion of multi-organ lesion is low. No significant difference of the sensitivity is found among langerin, CD1a and S-100 expression in diagnosis of LCH.