Primary Langerhans Cell Histiocytosis Associated With Multiple Lymphoepithelial Cysts: A Challenging Case.

A 64-year-old female presenting with multiple cystic lesions in bilateral parotid glands was clinically considered to be benign. The surgically resected specimen revealed that the lesions met the diagnostic criteria of lymphoepithelial cysts (LECs). What's unique is that Langerhans cell histiocytosis (LCH) were identified in the LECs by immunohistochemistry (IHC) and molecular test. The inconspicuous LCH cells distributed along and mimicked the epithelial lining of cyst walls and were possibly to be missed in diagnosis. To date, there has no documented report of primary LCH originating within LECs. This study presents for the first time of a unique growth pattern. In addition, we reviewed published articles and attempt to make tentative discussion on pathogenesis.